If you've ever released an App in the Android Marketplace and then had to update it then you've realized that there is no elegant way to inform the users what has actually changed. You can modify your app description but that really takes away a very valuable (and limited) space to describe your app and instead makes it into a small changelog. This is not ideal.
Google has heard your complaints and has introduced a revision history/changelog area into the Android Marketplace. We are super stoked about this because we just recently updated the DroidForums.net App to support proper landscape mode and bumped the version to 1.0.1 but didn't have much room to let the users know what really got changed in the update.
Google is huge, and so is the Android ecosystem... but with time, they do move and make changes. Here's to another positive step to continually improving the marketplace and the Android experience in general!
Full information at Google's website: Recent Changes - Android Market Help
As a side note, we also just released the DroidXForums.com version of our App here: The Droid X Forums Android App is Here!