A preview build of Android 3.0 is up, for devs eager to start licking some honeycomb. There's a list of new offerings, but chief among them are support for larger (tablet friendly!) UI design, and 3D acceleration.
The main features are clearly aimed at what's in store for Android (again—tablets) but a smattering of other new (minor) dev options are included as well. If this is your scene, give 'er a look. [Android Developers Blog]