Do you want to try Android 2.2 on your PC? Perhaps even try the sample applications and build them?
You can achieve this by these three: Eclipse + Android SDK + ADT Plugin For Eclipse
(There is also a native development tool, however it’s not for newbies)

1. Download and extract Eclipse (Choose IDE for Java Developers package)
2. Download, extract and run SDK Setup in Android SDK
3. Install the Android Development Toolkit in Eclipse
4. Point the ADK to the directory where you’re keeping your Android SDK files (the same place where you extracted the SDK)
5. Run Eclipse, find menu item under Window -> Android SDK and AVK Manager
6. Install available “Android 2.2 Revision 8″ into ADK. Check this screenshot (I already installed 8 so it doesn’t show):



7. Create new virtual device with the Revision 8 support and some memory space (I used 512mb here)



8. Finally, either start debugging sample applications or just run Android OS with the Start button in Virtual Devices panel.

Official blog says:

..“Pocketfox”, by Yaroslaff Chekunov. As the official emblem of the upcoming mobile version of Firefox, we’ll be using this image as an avatar on social networking sites, on mozilla.com, on t-shirts and more.

Pocketfox by Yaroslaff Chekunov