🙄 Not until next year.
Apparently XP SP3 will follow that.
Windows Vista Service Pack 1 Beta Overview (MS Whitepaper, pdf)
While Microsoft’s continued requests for businesses to not wait for SP1 before deploying Windows Vista may seem self-serving, this week’s revelations about the feature set of the service pack suggest that this advice is sound. Windows Vista SP1 looks like a solid and necessary update, but it will not dramatically impact the end user at all. If you’re a Windows enthusiast, Vista SP1 is more a curiosity than something to get excited about. It will not include anything interesting or compelling, in an end user sense, such as a new Media Center version. (Which is also overdue, incidentally.) Hopefully, this will end the speculation. I only wish Microsoft had been this upfront about SP1 months ago. It’s been a long time coming.