[Toadling]

OmniFocus automatically creates Spotlight metadata stubs for all "remaining" projects and single-action lists (i.e. active, on hold, etc., but not completed or dropped) in your database. You can see these stored at:

~/Library/Caches/Metadata/com.omnigroup.OmniFocus

When you do a Spotlight search that matches the name or contents of any of those items, the Finder will display the stub of the project/single-action list with the item's name among all the other matched files found. The file type for the stub is listed as:

com.omnigroup.omnifocus.project.metadata

If you double-click on one of the found items, OmniFocus will come to the front, open a new window, and display the found item with the matching search criteria highlighted.

One problem I've encountered, however, is that if the item found with Spotlight happens to be "on hold", when you double-click it in the Finder the new OmniFocus window just comes up and beeps without displaying the item. I'm going to send a bug report on this issue.