This is the simple steps to install an Android app development platform on Ubuntu 9.10. It's definitely not a clever method, but it works.

1. Install eclipse 3.5 bundled with Ubuntu:
   
   1. sudo apt-get install eclipse
2. Install these 3 eclipse plugins bundled with Ubuntu:
   
   1. sudo apt-get install eclipse-pde
3. Add the discovery site of Ganymede (eclipse 3.5)
   Ganymede Discovery Site
   http://download.eclipse.org/releases/ganymede/
4. Add the update manager sites that ADT is dependending:
   • Data Tools Platform (DTP)
     http://download.eclipse.org/datatools/updates
   • Web Tools Platform (WTP / WST)
     http://download.eclipse.org/webtools/updates
5. Of course you need to add the ADT update site it self:
   Android Development Tools (ADT)
   https://dl-ssl.google.com/android/eclipse/
6. Use the update manager to install ADT now.