Just over a year ago Apple released Aperture 3, which was a big upgrade over Aperture 2 in some key areas. Unfortunately the first few months (4-6) after the release there was little or no good publicity for the app and some Aperture users switched to Lightroom 3 because of all the bugs. To me that seems a little silly, it is not as if they couldn't have reverted to Aperture 2 till the bugs were fixed! In many ways that was too bad, because Aperture 3 really is a nice application, if it has the tools that you need. After a number of OS, RAW file support and application updates Aperture 3 seems to be a very stable application, which is what it should have been on release. My guess is Apple managers pushed up the release date to slow the shift of users to Lightroom, but in some cases they achieved the exact opposite.
If you are an Aperture 3 user and you are looking for Aperture tips, take a look at these two Aperture focused blogs if you haven't already: Aperture Expert and The Aperture Blog.