After a manual upgrade to Wp 3.1 my front page went blank, no error codes. The admin page was okay. Depending on which browser used I could some error about a redirect, but that was about it.
My site is experimental so it's not a disaster, but it was concerning. I didn't do any backups so reverting was not a good choice. Disabling all the plugins did not fix it.
After reading over the forums I found a fix for my site, it's a plug that fixes permalink and disables canonical redirects. My site came right up after activation.
I just wanted to re-post this for others who might have a similar issue.