Windows Vista build 5219 reports that it is Windows Vista Ultimate Edition--see my
Windows Vista Product Editions Preview for more information about the various product editions, or SKUs, that Microsoft plans for this release. That means that it includes both Media Center and Tablet PC functionality. (In Windows Vista, there will no longer be Media Center and Tablet PC Editions of the product.)
I have a lot more to say about the Media Center and Tablet PC functionality in Windows Vista, mostly because there are some new features in each when compared to today's shipping versions of XP Media Center Edition 2005 and XP Tablet PC Edition 2005, respectively, but I'll cover that in a future showcase.