Finally confirmation from Microsoft that there is a service pack for Vista coming and that there is a Service Pack 3 coming for XP
From reading the information from Microsoft the XP Service Pack looks like a roll-up of al the fixes since SP2 and doesn’t contain any features, but that is to be expected. What is more interesting is that Microsoft seem to be playing down the significance of the Vista Service Pack.
In addition to updates we’ve previously released, SP1 will contain changes focused on addressing specific reliability and performance issues we’ve identified via customer feedback, supporting new types of hardware, and adding support for several emerging standards. SP1 also makes additional improvements to the IT administration experience. We didn’t design SP1 as a vehicle for releasing new features; however, some existing components do gain enhanced functionality in SP1
So I don’t expect to see any major updates to Windows Media Center in the Service Pack, well nothing like the changes in XP2. I am sure it will have all the Media Center fixes and updates that have shipped since Vista was launched.
There is more information on the Windows Vista Blog and there is a detailed white paper.