I really like the favorite/boost/bookmark distinctions. I also like the fact that here you have to go back to the original post to talk--my brain says lovechild of Twitter and Pillowfort. Also, accountability, woohoo!

So. In my view.

Favorite: HEY YOU this was a COOL THING.

Boost: HEY EVERYONE this was a COOL THING.

Bookmark: HEY ME don't forget about this COOL THING.

Reply: OMG WHAT A COOL THING can we TALK about it?