For some time now I have had problems with eclipse giving 100% cpu when starting up. After making a new workspace and switching to it, I noticed Android dev tools no longer show up anywhere. In fact, File-New-project only shows "General" and "CVS" projects. I have ia32 libs, eclipse-jdt, but nothing shows up except in the Help-install new software, which says it's installed.
I have had a lot of issues with the Eclipse that is in the Ubuntu repositories. I've found it's much better to just dowload it and run it directly. If you're doing Android, I highly recommend the Android SDK/ADT bundle. It doesn't get much easier than that. If you need Eclipse for other projects you can get it at their website.
I ran Eclipse with sudo, updated and installed everything I needed, then ran
sudo chown -R username:username ./workspacedirectory. (Same with a .metadata directory, when I had problems later). This seems to be the solution! Strange, since sometime before 13.04 updates I though for sure I had tried something like this.