It involves generating seamless 'channels' from web content and locally stored content which are tailored to the user's preferences. These 'channels' would feel the same as network operated channels - A show - then an ad break - then another show ect.
One of the main reasons people are hesitant to pick up google tv - or any IPTV for that matter - is the fact that IPTVs are too 'active', when most people watch TV, they do it almost passively, they flick on the tv and watch whatever is on. There is an article on crunch gear about this I think.
I have already started building, but since Im new to C++ its out of reach at the moment