My parents live in Rural Florida (not a big city) and have DSL from a local ISP and SkyAngel, which is an IPTV provider. SkyAngel uses hardware and software from Neulion, and Neulion's stuff all seems fairly clever to me. The Discovery Channel is recently no longer available on SkyAngel. The reason for this is quite interesting!
My take on it is that the big cable and TV networks might have figured out that IPTV might be a threat to their business model and they have to try to pre-emptively put the IPTV providers out of business before they really catch on. My guess is that Discovery Channel, which makes most of its money from the big cable TV networks, was probably "told" to discontinue offering their programming on IPTV networks such as SkyAngel. I bet it was an offer they couldn't refuse, or something like that.
The official information is in press releases such as the one at http://www.skyangel.com/discovery . They paint it as a contract dispute. Of course SkyAngel has filed a complaint with the FCC or FTC or some regulatory agency. The legal battle is described on various blogs which you can find by googling "SkyAngel Discovery"
It will be interesting to see if the cable TV networks prevail on this one, and if they succeed in putting the upstart IPTV providers out of business before it catches on.