Microsoft has announced a partnership with Limelight Networks as the official 'content delivery network' for Xbox Live.
Limelight already provides content delivery, storage and hosting for Valve's Steam digital download network and Infinium's forthcoming Phantom console, as well as music services including BuyMusic.com, Musicmatch, and Real Networks
The terms of the agreement, according to Limelight, will be to help give "millions of gamers unprecedented online access to games, content and downloads from Microsoft and leading game developers directly via Xbox Live."
Although the current Xbox Live service includes some significant downloads, including the Xbox Live Arcade service, it seems likely that this announcement will also include next-gen Xbox Live, since "on-demand games and other multimedia content" are also prominently cited in the announcement, and Microsoft's Game Developers Conference keynote hinted at music services and other more fully-fledged digital downloads via Xbox Live.
Nathan Raciborski, chief network architect for Limelight Networks, commented on this announcement: "Microsoft's planned content and audience size presented massive performance and scalability requirements for this project. Our technology, distributed infrastructure, and proven delivery performance made Limelight the clear choice for delivery of high-speed downloads of Xbox Live content to a large and growing community of subscribers."