I used to think Yahoo! would be a major threat in the broadband TV space but lately have come to believe Apple is must better positioned because of their overwhelming breadth of products in the consumer entertainment space. Apple is now in an enviable position and if they play their cards right they will be a formidable competitor in delivering next-gen TV.
We know Google’s aspirations in this space as well so at this moment Apple, YouTube and Google are three of the companies to watch in the Internet TV market. Here is an article that delves a bit more into this topic — specifically as it relates to Apple.
Although this just hit me, it is worth sharing. I somehow see TiVo playing in the Internet TV space as well. They sort of are now but I see them realizing this is the next frontier for them, they are in a pretty good position to gain share in this market IMO.