Android 2.1 has been officially available on the Google Nexus One for nearly a week now, but the SDK had not -- until now.
There are a number of new APIs on board, including for the animated wallpapers, network signal detail, UI tweaks, geolocation permissions, databases. No real tells at first glance. No major resolution changes or super-duper space-age improvements. And unless you're a coder, none of this is for you. But the bottom line is it means newer and better apps are on the way.