The biggest changes were full Vista support and the removal of the 65,536 piece limit for torrents.
Also added was support for finding local peers (peers on the same LAN) and optionally not having any upload restrictions for them.
It is also possible to turn on automatic updating for betas now, found in the "Other" section of the preferences.
Fix: Disable Local Peer Discovery for private torrents
Internet and communication
Product page: here