I'm using WP 2.7 and earlier today WordPress indicated that six of my plugins had updates waiting. Excellent!
So I went into the Plugins area to upgrade, and selected the first one I saw to upgrade automatically. It upgraded successfully but then I noticed none of my other plugins were indicating that upgrades were available. It's almost as if it's stopped checking.
In this case the one I upgraded was WP-Email (2.31 to 2.4). I know for a fact that WP-Print has an upgrade waiting (2.31 installed, 2.4 just released today). So I know at the very least it should be indicating that needs to be upgraded.
Obviously I can upgrade them manually myself, but now that we have the auto-update option for plugins in WordPress it sure is handy and I'd hate to do without!! :)