It works. You can use almost any BT mouse and KB.
Trophies will be added (not the 3D Home ones), similar to the Achievements on LIVE in an upcoming firmware. Also, in game XMB is still coming (which update it appears in is a guess though), as well as the Blu-ray portable transfer to PSP, in game chat, etc. Of course, like always, these could be spread all over the place in several updates. I'm guessing that the trophies and chat will make the next one for sure though.
Somewhat related, YouTube can now be integrated in upcoming games. Not sure what for...maybe you can take a video of your game and upload it immediately or something.