Today I upgraded to Android SDK 2.3 and I also upgraded the Eclipse Plugin Androi Developer Tools 8.0 (from 0.9.9). I also upgraded my Java Development Kit to 1.6_22.
No
This problem was caused for my old projects on a new machine that did not have an older Android SDK installed.
To fix, simply go into project.properties and observe your old version number:
# Project target.
target=Google Inc.:Google APIs:3
Simply update the version number, like so:
# Project target.
target=Google Inc.:Google APIs:7
You will find that Eclipse then picks up the right SDK version and starts working.