Or, rather, Z to X, as the case may be.

Alongside the announcement of the Zune HD (to take on the iPod Touch), Microsoft has announced that the Zune video marketplace will supplant the current Xbox Live Video Marketplace on the console. No word on if the music store will follow or if Xbox-related videos will now be downloadable to through Zune’s PC software.

I think this integration has been a long time coming. Consider that ever since the Zune launched, it shared the same servers as Xbox Live content, shared the same “gamertag,” and used Microsoft Points from the same pool. (The last point makes Nintendo’s division of Wii-only points and DSi-only points an odd decision.) J Allard and many of Microsoft’s Entertainment & Devices group went from working on the Xbox to the Zune. It’s always all been in the same family with what seems to me minimal political hiccups getting in the way of synergy between the two brands.

The justification I’ve been using to explain that lack of cross-over was in the licensing terms. I’d figured that maybe some time early on when the umbrella terms were drafted, they called for media playback specifically only on the Xbox 360, not taking into consideration portability to other devices.

With the video store, it’s possible, though hopefully unlikely, to have purchased the same video on both the Zune and Xbox Live Video Marketplace. The smart user with a network would have only bought from the Zune storefront and streamed the video to their Xbox 360.

Personally, I’m hoping that I’ll be able to download all the gaming videos from the Xbox Live Video Marketplace to my PC, where hard drive space is more plentiful. I have a 120GB hard drive on my console, and it is chock full of gigs upon gigs of trailers, developer’s diaries, press conferences, and concerts. I need to regularly delete older demos just to make room for a new one, and there have been occasions I didn’t even have enough space to download a new Rock Band/Guitar Hero song.