As you'd expect, SP2 will include all of the patches that have come out since SP1. Microsoft is also planning a few notable feature additions, though. Here's a quick rundown of what you can look forward to, in Nash's words:
# Windows Vista SP2 adds Windows Search 4.0 for faster and improved relevancy in searches.
# Windows Vista SP2 contains the Bluetooth 2.1 Feature Pack supporting the most recent specification for Bluetooth Technology.
# Ability to record data on to Blu-Ray media natively in Windows Vista.
# Adds Windows Connect Now (WCN) to simplify Wi-Fi Configuration.
# Windows Vista SP2 enables the exFAT file system to support UTC timestamps, which allows correct file synchronization across time zones
.
http://techreport.com/discussions.x/15770
Vista SP2 to have Blu-ray write support, better search
Vista SP2 to have Blu-ray write support, better search 
