Maybe it is all the TV news mentions, but Twitter is seeing the growth in U.S visitors to its site accelerating. In February, 4 million people in the U.S. visited the site, up from 2.6 million the month before, according to the latest data from comScore. That represents a 55 percent month-over-month growth rate, compared to 33 percent growth in each of the two months prior. (ComScore has yet to release February figures for worldwide visitors, but for January that number is 6 million).

These numbers are only for visitors to Twitter.com, and they do not capture usage on desktop or mobile clients. And the apps just keep on coming. For instance, Twitdom now counts 529 Twitter apps. But the site visitor numbers are indicative of the steep growth ramp Twitter is enjoying right now. It is still early days. Can its growth keep accelerating or is it unsustainable?

This week’s elevator pitch comes from HerHotSpot.com, an online community for Gen Y women to share stories, ask questions, and get advice on life, love, fashion, work and health. While the name is regrettable, the pitch by founder Brette Borow is well articulated and she does a good job of getting her points across. Launched last year, HerHotSpot is trying to merge the social features of Twitter and Facebook with the content that magazines like Glamour or Cosmopolitan provide.

The site itself is geared towards several major issues in a Gen Y woman’s life—health, style, love, post-college life, work and pop culture. Part commentary from professional writers and part user-generated content, the site allows readers to post their own content and, like with Twitter, readers can follow other participants. Users can post video content as well. HerHotSpot is trying to be a content network as well as a social network, creating one big online forum that looks similar to the Sugar Network’s PopSugar. Instead of reinventing the social network wheel, HerHotSpot is hoping to get an influx of members by integrating with Facebook Connect.

(Video pitch after the jump)

When Lance Armstrong sat down with John Battelle at the Web 2.0 Summit last November, he had been twittering for about 10 days and was jokingly asking that “shoe guy” to send some followers his way. Now four months later, even Richard Rosenblatt, CEO of Demand Media and the guy who helped get Lance into Twitter, has been surprised by how much @lancearmstrong has taken to the platform: twittering and twitpic’n about training, races, travel, family, food, movies, and his mission to grow the fight against cancer.

For those of you interested in more than 140 characters, Lance took some time out to discuss his new habit.

Q: You started using Twitter back in November. You are now closing in on 300,000 followers and you tweet more times per day than most people brush their teeth. Can you point to a couple of factors that have resonated with you making Twitter part of your daily routine?

Lance Armstrong: Well, 140 characters fits my personality well. I’m not much for small talk so 140 gets me that. I see long drawn out emails and I delete them. It also brings a certain transparency to my life that others may have never seen or realized. Lastly, it works great for talking about the thing I care about the most (behind my family) and that’s fighting cancer. Twitter builds grassroots movements quicker than anything I’ve ever seen.

We’re here at SXSW, where Facebook’s Senior Platform Manager Dave Morin is speaking about The Search for a More Social Web.

He says that computers have largely been antisocial - it was only with the advent of the computer that we’ve been playing games with ourselves. Only in the last few years have computers really started to become social. The introduction of Facebook’s new real-time homepage has offered a big boost to becoming more social. Facebook’s new Pages allows us to follow the actions of our favorite brands and celebrities throughout the day.

Gary Vaynerchuk has taken the stage. Vaynerchuk has begun to produce content on a new public profile, and is also offering some of his thoughts on the switch from a regular profile to his new Page. “I wanted more than 5,000 friends, that’s really what this allows me to do”. Vaynerchuk says that people are talking too much - this new product on Facebook allows people to listen, which is a key part of interaction. “It also saves me around 40 Emails a day of people asking for my friend requests”.

We’ve got one of Casio’s Exilim FC-100s for review right now, and of course the first thing we had to do was test out its vaunted super slow motion functionality. I was going to save this little reel for the review, but it was too fun not to share.

Yesterday was a particularly bad Friday the 13th at Spot Runner, the Los Angeles startup that is trying to Web advertising techniques to TV. The company told employees it would need to go through its third major round of layoffs in less than a year. At least 60 people were told the would be let go, the company confirms. We’ve added the 60 to our Layoff Tracker.

This is on top of the 115 employees who lost their jobs last November and the 50 more last August. Throw in natural attrition, and the company, which at one point numbered more than 500 employees, could soon be down to less than 120 people.

The layoffs supposedly triggered the WARN Act, which requires companies to give employees 60 days notice for any mass layoff—defined as 33 percent or more of the active workforce. That would suggest Spot Runner currently employs less than 180 people, and after the layoffs take effect will employ less than the 120 mentioned above. Spokesperson Rosabel Tao disputes that math, saying, “As a private company, we do not disclose employee figures but it is out of hundreds.” She also notes that the California WARN Act is more stringent than the federal one and requires notice if 50 or more employees are effected, regardless of the percentage.

Tips started coming in to us yesterday. One mentioned that Spot Runner employees were updating their Facebook statuses with references to “suite 2160,” the conference room where the last round of layoffs took place.

TechCrunch UK & Europe recently hosted a Roundtable & Meetup in Paris. Despite issues getting a live video stream and uploading the videos “TechCrunchTalk: What Next For France 2.0?” featured an afternoon of panel discussions with French startups and the investment community. The kinds of things that were discussed were pretty interesting, and something of a metaphor for the issues continental European startups face today.

A week ago we reported that blogger Robert Scoble is leaving his current job running FastCompany TV. Now he’s going to start talking about his new project - a new content and social networking community called Building 43, which he’s building in partnership with his new employer, Rackspace.

More details will be announced on the Gillmor Gang at 3 p.m. Saturday (today, Pacific Time) live at TWiT Live. Scoble will join Steve Gillmor live via Skype from Rackspace’s offices in Austin, Texas.

Regarding the name Building 43: “The first time I visited Google they gave me a tour of Building 43. I found it to be a fanciful place where not only did the founders have offices, but they had this fun board in the lobby called “Google’s Master Plan.” VC Steve Jurvetson has a picture of that board here - seemed like a good metaphor for a community that’s for people who are fanatical about the Internet. Make Building 43 open to everyone.”