A few days ago I installed the android SDK and the ADT plugin for eclipse. When I started playing with the android API I was a little disappointed. I was missing the source attachment for the android.jar which contains the android API. I was searching the web for the android sources jar and found a guide how to create an android sources jar .
I've adapted the sources howto and created my own android sources jar for android platform 7 aka android 2.1. You can download it here: http://www.bughome.de/android/platforms/android-7/android-src.jar
I'm pretty sure that the android-src.jar is missing some sources, because the source jar is smaller than the binary jar. Comment me if you find the missing sources.