I haven't seen much about this in the forums (I am sure someone can correct me if I'm wrong), but I had upgraded to WordPress 3.0.5, and now my website has disappeared. My login page and all of the internal editing and managing tools are still available, so I thought it was a plugin problem (since I had just upgraded about 8 or 9 other plugins that same day), and on Firefox, I got a blank (no source code either) web page (located at http://sj.foodsci.info).
On IE8, which was a little more informative, it told me I received an "Error 500: Internal Server Error". Nothing actionable though.
Downgrading to 3.0.4 didn't work either.
Any ideas or clues?