Boxee is breaking the mold it set for itself and will now begin to include a new Boxee Live TV Tuner according to GigaOm who got an unreleased version of the Boxee 1.5 update which will be released soon.
From their article it seems that Live TV is ready to be integrated into the Boxee Box. On the downside, it looks to require a USB digital TV tuner and antenna, though you can apparently also plug in coax.
The thing that this really does is combine your online on-demand viewing with your Live TV viewing and doesn't require a cable box. Granted, you'll just get the local TV channels or the unencrypted channels on the cable line. But if you live in an area with plenty of digital TV signal and don't want to pay a cable company this might become a viable solution for you. However, there isn't any DVR capability so far I think.
This is just the continuation of screen convergence in my book. Google TV can do it, but you need a cable box. The Microsoft Xbox 360 is set to incorporate Live TV, but again, you probably need some adapter or box and there's no telling when it will arrive in any specific market. Right now, I still think that a media PC is still the best way to achieve it all as you can pull content online and with the proper TV tuner card can pull in a lot of content.