Google finally release the 2.1 SDK yesterday.  Details can be found at developer.android.com.

There is not a whole lot of new stuff in 2.1 over the 2.0.1 release, but there are a few tidbits:

Live Wallpapers

The following additions provide APIs for you to develop animated wallpapers:
* New android.service.wallpaper package.
* New WallpaperInfo class.
* Updated WallpaperManager.

Telephony

* New SignalStrength class provides information about the device’s current network signal. This can be acquired from the new onSignalStrengthsChanged(SignalStrength) callback.
* New onDataConnectionStateChanged(int, int) callback.

Views

* New View methods isOpaque() and onDrawScrollBars(Canvas).
* New RemoteViews methods addView(int, RemoteViews) and removeAllViews(int).
* New ViewGroup methods isChildrenDrawingOrderEnabled() and setChildrenDrawingOrderEnabled(boolean).

WebKit

* New WebStorage methods to manipulate web storage databases.
* New GeolocationPermissions methods to get Geolocation permissions from, and set them on the WebView.
* New WebSettings methods to manage settings for app cache, web storage, and zooming based on screen density.
* New WebChromeClient methods for handling video, browsing history, custom Views, app cache limits, and more.

API differences report

For a detailed view of all API changes in Android 2.1 (API Level 7), as compared to API Level 6, see the API Differences Report.