My Gmail switched today to the new v2 UI (ui=2 in the address bar). It’s great, although I don’t notice any obvious UI changes, it feels faster. Most emails open instantly. There is a bit of a delay for the new yellow loading indicator to appear at the top which gives the impression the interface has stalled for a bit. It’s a slow roll out I guess because a couple of my other Google Apps accounts don’t have the change reflected yet.