Maybe I am too much of a geek, but I actually enjoy reading application version updates. I assume most people do not read them thoroughly (many do not regularly update their apps either), but it is a really simple way to communicate with users and share what's new. It is so simple to do... and yet so often forgotten.
Most app updates read something along the lines of: - "fixed crashes" - "fixed various bugs" - "app runs faster"
In fact, I've seen many that say "the free version now has ads". Yeah, that's going to make me download the update!
Here are three great examples from three great apps: Foursquare, Path and Square. I particularly like the Path update because the app underwent a significant product change... this update is their first opportunity to introduce existing users to the changes. Of course, the app experience itself should also introduce / familiarize those changes.... but this is such an easy way to get started. And because so many developers overlook it, the mere attempt to communicate changes distinguishes these apps: