yup, same here...
i think installer must keep a list of installed apps in a location that's not overwritten during the update to 1.1.1.
even though third party apps (including installer) are wiped out during the 1.1.1 update, they're still listed as installed once you reinstall installer (installer is listed as being 3.0 in the "uninstall" section, so it must think it's already updated). if we knew where installer keeps its data, we could probably just delete some file to reinitialize it.
you guys probably updated installer during 1.0.2 like i did. i think we wouldn't have this problem if we didn't update before the 1.1.1 conversion. once a newer version than 3.0 is available, it will probably show up in updates.
***UPDATE***
found the solution...
http://www.philmug.ph/forum/showthread.php?t=27137