Microsoft is beta-testing Service Pack 2 for Windows Vista SP1 and Windows Server 2008 -- which are based on the same code -- and will make it available to everyone tomorrow through a Customer Preview Program (CPP). On the Windows Team Blog, Mike Nash says:
CPP is intended for technology enthusiasts, developers, and IT Pros who would like to test Service Pack 2 in their environments and with their applications prior to final release. For most customers, our best advice would be to wait until the final release prior to installing this service pack.
The final release will be "in the first half of 2009," possibly in April.
As usual, SP2 includes a roll-up of all the fixes developed (but not necessarily published) since SP1. Microsoft has published a long list as Notable Changes in Windows Server 2008 SP2 Beta and Windows Vista SP2 Beta.
Some improvements are things you might have downloaded separately, such as Search 4 and the .Net Framework 3.5 SP1. Vista SP2 also includes the hyperviser, Hyper-V, which lets you virtualise servers. (Not for the faint-hearted.) Also, the built in support for Bluetooth and Wi-Fi gets upgraded. Mary-Jo Foley has a longer list in Vista SP2: What's inside? No doubt the reviews will provide more info.
It will be interesting to see if SP2 makes much difference to Vista, because SP1 fixed most of the problems that Microsoft could do something about, and provided a noticeable improvement in performance on some low-end hardware. I think it's unlikely to have the sort of dramatic effect that XP SP2 had, simply because there isn't as much needs fixing.
Microsoft hasn't released Vista sales figures recently but Net Applications puts its market share (of the installed base of net users) at about 20%. Since its monitoring appears to understate XP, it could be higher.
