Windows Vista SP2 beta was released recently! This beta is available for download from Technet and MSDN both for subscribers and the public.
There are several enhancements in the service pack. Here is a list of things that, to my opinion, stand out from the list:

• Bluetooth 2.1 feature pack supporting the most recent specification for Bluetooth technology
• Record data on Blu-Ray media
• exFAT file system now supports UTC timestamps, which enables correct file synchronization across time zones
• Resume performance when Wi-Fi connection is no longer available after resume from sleep
• Inclusion of Windows Search 4 for improved indexing performance,  improved relevancy in search, broader indexing scenario inclusion
• Single installer for both Vista & Server 2008. (I'm not sure what that means. One Service Pack for Vista and Server 2008? That would be really cool!)
• Inclusion of Hyper-V
• Windows Vista Feature Pack for Wireless. (I can't wait to find out what this is!)
• Reduction of resources required for sidebar gadgets. (I have to see this! Maybe this will make me bring back my sidebar which until now was always closed!)

And last but not least, SP2 includes all previously released security updates, and builds on the proven security benefits of Windows Vista. So if you install a new Vista instance you just need to install SP2 and your are safe and done.