Solution for me:
BACK UP YOUR CODE!
Navigate to your project workspace (not your project) and run the following commands:
dev1:workspace$ cd ~/Documents/workspace/.metadata/.plugins/ dev1:workspace$ rm -rf org.eclipse.core.resources
Navigate to your Eclipse directory and type this command:
dev1:eclipse$ ./eclipse clear
Eclipse will start with an empty workspace - don't worry your projects are still there. Simple create new project from existing resource and things should be gravy.
The exact error I was receiving: [2012-02-07 14:15:53 - Dex Loader] Unable to execute dex: Multiple dex files define Landroid/support/v4/view/PagerAdapter; [2012-02-07 14:15:53 - PocketCloud]ProjectCloud] Conversion to Dalvik format failed: Unable to execute dex: Multiple dex files define Landroid/support/v4/view/PagerAdapter;