This means developers for the Android platform can download the 2.1 SDK from the SDK Manager and begin building applications with it.
Google's Android team described Android 2.1 as a "minor platform release" that includes API changes and bug fixes.
The platform includes an Android library and system image, as well as a set of emulator skins and sample applications.
Specifically, changes in 2.1 include APIs to let programmers write "live" or animate wallpapers; new class to provide information about the device's current network signal; new view methods; and changes to the WebKit browser engine underpinning Android.
For example, Android 2.1 includes new methods to manipulate Web storage databases; new methods to get geolocation permissions and set them; new methods to manage settings for application cache, Web storage, and zooming based on screen density; and new methods for handling video, browsing history, custom views and app cache limits.
Currently, Android 2.1 is available on the Nexus One, but some enterprising modders have patched 2.1 onto the Motorola Droid, the previous dominant Android phone Verizon Wireless began offering in November.
When Droid owners learned of 2.1 appearing on the Nexus One, they immediately called for Motorola to add it to the Droid. Motorola complied, vowing to add 2.1 for the Droid and the Motorola Cliq soon.
By most accounts, Android 2.1 is faster, though it's tough to tell from eWEEK's tests of it on the Nexus One.
This is because the Nexus One runs on the Qualcomm Snapdragon 1 GHz processor, making it hard to tell what accounts for the smartphone's speed bump over the Droid and other Android predecessors.
When Motorola does push through the upgrade from Android 2.0 to 2.1, it should be easier to see the speed improvement.