I have some problems with Gnome 3 (Gnome Shell) with the Nvidia 3. The main thing is that sometimes texts will get corrupted when you scroll down a website under Firefox. It can take some efforts to to click some links in Firefox for some websites (like the links below any LinuxToday articles). The first link is there, but when you scroll down and try to click it, it disappeas and the text below that becomes corrupted. Most likely it is an Nvidia driver problem but I have updated to the latest version from Arch. And I do not have such a problem under Ubuntu 11.04 with Unity.
In the end the workaround provided in Arch Forum works, press ALT+F2 and type "r" and then everything is fine.
Quote from that Arch Forum article:
"Have you tried Alt+F2 to open a command prompt then entering r ? I think I get the same thing you get when I come out of suspend and r at the command prompt resets the Gnome Shell and fixes the problem. I'm also using the closed source Nvidia driver."
Notes added on 17 July 2011: it still does not work well, still has the garbled text problem. So I just switched to the Fall Back mode by default.
Notes added on 21 July 2011: it seems that the latest NVidia driver improved on the issue (275.19-1 version) but I still see text corruption when scrolling with a mouse under Firefox and Gnome 3.