1 vs. 100, the free Xbox Live game show open to, theoretically, everyone, is telling U.S. players "the game session is full" on the first day of the beta.
The U.S.'s first live beta event was scheduled for 10:30 p.m. EDT. At that time, having already downloaded the beta, I got an error screen (GO29) telling me "the game session is full." This is, I mean literally, at the first minute the game was supposed to go live.
Update: Through 1 vs. 100's official Tweet, we're all being advised to get in early, as participation will be on a first-come, first-served basis. No word on any maximum participation size. But 1 vs. 100 live host Chris Cashman, who referred throughout the evening to the 50,000 in attendance, mentioned that the capacity limit will be removed for the Saturday show. Other Microsoft types had been Tweeting about the stress on the system, so perhaps this was a test.
Figuring I perhaps had a corrupted file (possibly from the Canadian beta gate crash?) I redownloaded the beta. I still got the same error message, and further, when trying to activate the game through the download history of my account management tab, got the following:
I Tweeted Major Nelson about this (no reply yet) but several who follow my account mentioned they had the same error; virtually all my XBL friends (including, of course, Hardcasual) complained of the same thing. And further, via Tweet, a participant actually in the game said 1 vs 100's online host mentioned more than 50,000 people were in the first night's live episode. That speaks very well of the game's demand for MIcrosoft. But compared to the roughly 8 million Xbox Live gold members, it's a problem.
This is total speculation that an actual participation cap is in place, and that this isn't another kind of error or overload. Still, no maximum has been mentioned in the preceding discussion of the game. And it doesn't change the fact that a lot of people are on the outside looking in on 1 vs 100's debut night in the United States. More if it develops.