I tested the fedora 12 x64 Beta. I was very happy, it ran very fast. After playing sometime, I opened firefox when the stupid display corruption occurred.
To the very new guys to fedora and nouveau, here is the summary. Nouveau is a open source driver for nvidia cards and Fedora 11 and Fedora 12 uses nouveau driver by default if you have nvidia cards in your system. The open source nouveau driver is very good, but somewhere in some scenario corrupts the screen display and hangs the system. Hope this bug gone and Fedora 12 rocks as usual when it releases
I could not take the screenshot of the corrupted screen as everything hung. I took photograph using my digicam and they are attached here. I will raise the bug in bugzilla soon (may be this weekend) which I already raised for Fedora 11 (https://bugzilla.redhat.com/show_bug.cgi?id=505853)
If you want to read more about how I booted into Fedora 12 and used vesa driver instead of nouveau, you can have a look by clicking the following link