Aiming to one-up (or rather, eight-up) DirecTV's promise of 100 HD channels by year's end, Comcast is boasting that it will have over 800 HD channels by the end of 2008. If, that is, you consider an endless run of CSI episodes and a perpetual loop of Ghost Rider to each be their own channels. Sure, a Heroes "channel" is a channel in a certain sense, but not in the typical television parlance consumers are accustomed to.
Why is Comcast making with the verbal jujitsu?
First and foremost, for the same reason the 800 number made your eyes pop out: There simply isn't that much HD content to go around. As Ars notes, most cable networks "have yet to commit to launching HD versions of their programming," so even the 100 channels DirecTV tossed out brought its share of skeptics. What's out there is growing, for sure, but the market's far from mature, so there's a wide gap to fill.
Problem two is bandwidth—HD content devours it, and cable companies only have so much. One solution is Switched Digital Video, which only sends content to your home from the neighborhood node after you've requested it, selectively using only the necessary amount of bandwidth. Of course, IPTV only requires transmission of a few channels at a time, giving it an edge in this particular area.
Bottom line? Despite the growing number of HDTVs landing in homes, hurdles on both the content and technology sides are going to limit what's on and what's available for at least a while longer, whatever big numbers the cable and satellite companies might throw at you.