I take it back, I've got NSUserActivity indexing to work on b3.
I've narrowed the issue down to the following:
If i set a relatedUniqueIdentifier (to anything) in a CSSearchableItemAttributeSet which is assigned to the NSUserActivity, the item doesn't get indexed.
If I leave the item without a uniqueID, it gets indexed.
This however poses a problem in regards to the whole de-duplication thing!
If I have time tomorrow I'll post a radar. Anyone else have this issue? Just me?