This is something that's been needed to happen for years now, but it seems as though Microsoft's Windows Store will obviously include downloadable apps, where the Xbox and Windows brands will finally merge into one ultimate champion of awesomeness.
There was a list of recent Xbox Live games that The Verge reported on, that would be made available to purchase within the Windows 8 Consumer Preview version. Sources have now confirmed with The Daily that these games will be set within Windows' first Xbox-branded portal, instead of the older "Games for Windows" platform. This will now completely integrate Xbox functionality, including achievements and friends lists, and will look like the recent Xbox Live app for iPad in terms of design.
The preview version of Windows 8 will sell older games, but sources are saying that some games currently in development for Xbox Live will be deliberately delayed to launch with Windows 8 in September. Names of these games have not yet been revealed, but sources are saying that they're a mix of "casual and hardcore" games, some of which have already been announced as future Xbox Live-based titles.