New shiny kernel, new patched wifi drivers, compiz working out of the box (so we can all pwn like r0ckstarz). We are planning on new public repositories for BT3 - for better support for updates and HD installs.
We still don't have an ETA for BT3...but one thing is for sure - it will be worth the wait! More info about BT3 dev to follow in the next few weeks.
PS - I've updated the offsec website with this BackTrack 3 Teaser: