The OP misspoke slightly, but sometimes stuff can get confusing. The iPhone is the biggest selling phone in the United States, yes, even more than the freebie RAZR (cite). They had 28% back in February of 2008 and now have 30% as of December 2, 2008 -- although the later figure seems more suspect (cite, cite). The supply drop of iPhone-2Gs in the 1Q diminished their numbers quite a bit. Also, the market is smart phones, not just touch screen ones. The largest player in smart phones in the US is Blackberry -- which, well, has been having a less than stellar time with the attempt at the touch screen Storm.

cable company is REQUIRED by fcc to give customers cable boxes with firewire out.

myth tv can control almost all firewire boxes just fine.

While it is currently true that the FCC has regulations regarding the availability of firewire controllable cable boxes, the regulations do NOT state that the encryption level must be changed. I used a cable box with firewire for two years in MythTV setup. The only channel I received over firewire that was not available via unencrypted QAM was Universal HD, and I'm pretty sure that was a mistake. All the other channels that were encrypted over QAM were still encrypted on firewire.

The only alternative that you have right now is the Hauppauge HD-PVR, which captures analog component and transcodes it to H.264. Of course, this device isn't fully supported yet. It's an exciting future, but not quite there.

Even at the point that where the HD-PVR becomes fully functional, you'll still need to drive it with a cable box.

There is also question about how long the firewire "standard" will remain. At the recent FCC hearing on the campus of Carnegie Mellon University, Intel made it very clear that they were pushing for IP based technologies and thought that the firewire standard had failed.