Easy way to generate “release notes” on GitHub
Assuming you're using tags with your git repository on GitHub, it's rather easy to generate something resembling "release notes"; or at least, a list of descriptions of all changes between two tags. That's pretty much the same thing, right? Anyway, if you go to "/compare/tag1...tag2" under a project on GitHub, it'll show you everything that changed between those two tags. Here's an example: Radiant's changes between 0.9.0 and 0.9.1. Neat, huh? If not used as the actual release notes, it can at least help you remember all that changed between two releases when you handcraft a list yourself.
This feature was announced March 1, 2010, but it's hard to find unless you know you're looking for "compare view" 
. It's also sort of hard to find -- you have to go to the Source tab, then Branch List, then hit the Compare button on a random branch, and then, finally, you can input a start and end tag in the upper right. Easy to find, no?