Search "IPTV" into google or something.
There already are some services available. Cinemanow being the biggest as far as Videos. http://www.cinemanow.com/home.aspx
TV content is still slow coming from the big content providers. Most of them like Disney don't see a point in changing or making any deals with the telcos for their new IPTV services. So it maybe a while before you start to see the mainstream content providers offering streaming video. I wish History Channel would, since that is about all I watch.
When the local teleco rewires your neighborhood with fiber-optic lines in place of the copper, bandwidth capabilities will allow them to then offer TV, high-speed internet, etc. In my neighborhood, Verizon will convert phone lines to fiber optic within the next 2 years. Interestingly, I got this info not from the companies website, but from a local installer/ DSL service tech.
Probably from a cable broadband company (like Comcast) or a DSL provider (like Verizon). I thought I heard Verizon was trying to do something like this. Either might have info.