Yes, this is very much an "Apple rumour", just ahead of Steve Jobs' keynote address to MacWorld on January 6th:
The iBox plugs into your TV and acts as a hub for your digital devices and computers. Unlike the EyeTV from Elgato, the iBox is a standalone machine, not something to plug into an existing computer. The iBox can be scheduled to record TV, but unlike TiVos it does not serve as a "what's on and when" service rather a hard drive / media based recording device (new aged VCR). With its built in 802.11b & 802.11g from its AirPort Extreme card, one can access the home folders of any user on any wirelessly networked Mac or PC. The iBox has its own version of the popular iPhoto and iTunes software which is a welcoming plus to Mac OS 10 veterans and easy for Windows users to adopt as well.
I see this as being a very plausible device, although it's not clear to me how the OS would differ. I would expect the same BSD-base to be used, and then (I guess) a slightly modified version of Quartz, optimized for a "10 foot interface" of being displayed on a TV.
Whatever the truth, I'm definitely going to be watching the keynote broadcast at 9am Tuesday morning.