Nope, u r not the only one. I just tried to play a game, but it just keeps crashing and I keep getting the rainbow circle anytime I try to connect to a game.
I was noticing a LOT of TF2 crashes in Lion, right around the release of their "Manniversary" update (but also at the same time Apple released OS X 10.7.2, making it hard to tell exactly what was the culprit).
Since Windows users were complaining too though, pretty sure it was the TF2 update causing most, if not all, of the issues.
Anyway, I played it quite a bit over the weekend without any crashes so the latest update seems to have fixed it again!
(I will say though, I noticed a few times when the gameplay appeared to freeze momentarily, and then picked right back up where it left off. I got the feeling that was a spot where I would have seen a crash before. So I'm wondering if Valve coded more of a work-around than a total fix, so if something fails/crashes internally, it just resets and continues now?)
Pretty sure it's just from the "Manniversary" update, as I've noticed a LOT of Windows users on the Steam forums talking about it. It worked fine before that update, so be patient I'd say.