Whidbey - Hosed
Whidbey finally gave up on my machine. All of the controls in the toolbox are greyed out, but I can copy controls from other forms onto the form I'm working on. The properties dialog also is non-functional (greyed out). On the plus side, I'll get to test out the “Restore installation to its initial state” feature in Whidbey. I'll update this post with the results of the attempted repair.
Update - It turns out this was due to “VSCorePackage” getting corrupted. Restoring Whidbey helped a bit, but it's still acting a little odd. It looks like “devenv /resetskippkgs” might have saved me the trouble though.