Brightkite for Android is the best version yet
The long-awaited app - there were reports over a year ago that it was in the works - takes advantage of Android's built in Google maps to let you visualize your friends' locations instead of reading them in a list. It also uses Android's notifications to alert you to any new activity in your friend stream. As an iPhone owner, I'm loathe to it admit it, but this looks even better than the iPhone version of the app. The maps, especially, are a great touch.