Hmmmm, it seems the feature isn't fully satisfying to me.
- "New" post to a thread, won't stack at top, but still be scatterd across the board.
- can't get rid of old threads, but only collaps them with "Vote down".
- can't see if I'v already been posting in the thread, and can't find my posts in various other sections other than "My Posts"
I liked my old PF.com features which Imo was almost superior, just that I manually had to unsubscribe (in a very clumbsy way) each and every thread to avoid e-mail spamming.