Just upgraded my wordpress blog to the latest version. All seemed to go OK but when I looked at the blog all I got was a blank page. After a few hours of searching I finally got it up and working again. For any one else in the same position (and as reminder to myself for the next time!!)
1. turn off all plugins
2. after loading the new code dont forget to load any plugins and themes you are using
Probably best to install the new version over the old version that way all the plugins will still be there.