The Xbox should finally be receiving two much-anticipated video features tomorrow, according to a source at GigaOm. HBO Go and Comcast Xfinity On Demand apps are both reportedly slated to launch, which is exactly the right timing for the new season of HBO's Game of Thrones. HBO Go on Xbox was actually originally set for launch on April 1st, but the company said that it would want to launch a few days before to make sure that there weren't any issues with customers getting the new features on the same day as the premiere.
As for Comcast's Xfinity On Demand service, we had already heard it would be launching soon from the company's own site, and notably video streamed via that service won't count against data caps since it's being delivered over Comcast's "private IP network and not the public internet." Presumably the same won't apply to HBO Go video, so Comcast customers with both shouldn't stop watching their bandwidth caps just yet.