1. First of all, in Impulse, make sure you have "Show pre-release versions" checked.

2. Check out this thread: http://forums.wincustomize.com/?postid=367639
From which comes this statement:
On December 2, 2009, Object Desktop and Object Desktop Ultimate will be merged into Object Desktop. Users with Object Desktop Ultimate will get a full year added to their account (so now is the ideal time to pick up Object Desktop Ultimate).