I have used the "upgrade automatically" feature in the past without issue, but for the last few version updates (3.0.3 and 3.0.4 for sure) I click on it, fill in my password, and am given a contentless page.
The page has the standard WordPress navigation (Dashboard, etc.) and the notification that I should upgrade to 3.0.4. But there is nothing else there.
This happens in both upgrading WordPress and plugins. Which is annoying. :-)
I know I can upgrade manually - that's what I do to solve this. But it would be nice if the automatic upgrade were working again.