Its actually been there in the Playstation store since early December (the 11th i think it was). And yeah its an awesome service.. If you do a search on here you would have found topics on VidZone already. :)
I'm on Telecom 40 GB cap. The most I can see in the weekend is 230 Mb on one day we used Vidzone for hours on end. Although it is hard to tell what else we were doing online that day (I play multiplayer games a lot). For example, I can also see 6 GB used on Christmas Day when we also played the whole Vidzone Christmas songs playlist plus others.