In short, it probably won’t mean much to the Media Center community right off the bat. But, that could change as time goes by. And not just for Media Center users, but for all HTPC enthusiasts in general.
The SDK is expected early next year and I would imagine that many Media Center developers will begin projects soon after that. What will those projects look like? I have no idea. But, I have no doubt it will be ported into Media Center in short order. It probably will run on your current HTPC hardware. The only required “upgrade” may be to an HTML5-compliant browser.
It may not be a competitor to Media Center, but instead, a partner.
I think the biggest question, at the moment, may surround Bing. Yes, Bing. In case you haven’t noticed, they have recently added a LOT of interesting media features. Try searching for a TV show and you will find links to sites where you can watch episodes of the show, such as Hulu, the network website, etc. You’ll also find episode guides, links to purchase the DVD’s, and all sorts of other relevant information. But the big one is the links to watch episodes. If this can be packaged up and added into Media Center then it may do what Google TV will do and beat them to the punch.
But, I doubt that is all that Google TV will be. We won’t know for a while yet, but I suspect Google may have one or two surprises in store. And, with it being open-source, developers can added a lot more surprises. It can only mean better things for HTPC enthusiasts.