I wasn't entirely sure if this technology was going to affect the cable industry at large, and it sounds like it won't. The need for a dedicated USB adapter will only affect certain specific devices -- a few TVs with integrated cable tuners, and TiVo boxes -- with the TiVos being the highest-profile category, of course.

Is this a good thing for TiVo users? That's a trickier question.

After chatting with some executives from CableLabs who asked not to be named, a few things are clear: the mysterious USB adapter will be leased from the individual cable provider, alongside things like CableCards. The cynic in me suspects that TiVo owners could get stung rather hard by this, because cable owners have an incentive to sell their own PVRs.

The reason that TiVos require the adapter is that they're unidirectional devices, at least where cable is concerned; switched video multicasts only requested channels out to cable boxes, so a return channel is required.

So we've briefly touched on the disadvantages: some sort of leased USB adapter that you'll likely pay some fee for. What's the upside? Well, according to an ex parte letter that TiVo sent to the FCC this week, the adapter means that a TiVo will itself be a set-top box, capable of its own video-on-demand services. That will allow more viewer input in the selection of TiVo and cable services, although admittedly one of the strengths of TiVo is its ability to recommend new shows.

There's one oddity, though: apparently TiVo wants to build an entirely new box that's compatible with the OpenCable Application Platform. According to the letter, TiVo apparently proposed (or is amenable to) that box including both a "TiVo mode", where DVR functionality would be enabled, and a "Cable Mode," where DVR capabilities would be turned off, but cable services enabled. Interesting stuff.

Final thought: while the need to buy a USB adapter would seem to have a chilling effect on TiVo usage, the letter's tone certainly doesn't indicate that. Either I'm reading it incorrectly or TiVo has concluded that its most financially viable solution is to get consumers to upgrade, again.