While the iTunes Store is primarily known for music, it's also the 100-pound gorilla of the video download market as well, having already sold literally millions of TV episodes at $1.99 a pop, and now full-length movies too. In September, Apple added Disney movies to its lineup of network shows, and, more importantly, increased the video resolution to near-DVD quality. This upgrade means that shows will now look great on your laptop in full-screen mode, as well as on your 2-inch iPod display. The caveat, as always, is that Apple uses a proprietary encryption format that requires iTunes and QuickTime for playback, so videos won't play on any portable players but Apple's.

Amazon's upstart Unbox service seems poised to challenge the iTunes Store for video supremacy, thanks to a highly visible launch pad, and a broader selection of movies. Studios like Sony, Universal and Paramount have all signed up with Unbox, whereas only the Disney studios are currently in the iTunes fold. Unbox videos can be rented for 30-day periods as well as purchased outright. The downside is that purchased Unbox movies can be more expensive than DVDs, yet can't be burned to DVD. And you can only watch them on authorized PCs and handheld devices that have Amazon's player installed, which doesn't work on the Mac OS.

The big three cellular providers all have streaming video services on their 3G networks, although the content varies widely. Only Sprint TV has actual live shows. Cingular Video and Verizon VCast only offer pre-packaged video clips and movie previews, mostly supplied by the big networks and studios. Think of it as airline video fare, without the full-length movies. You'll find lots of news and sports segments, music videos, and highlights of primetime shows. Pricing also varies widely, Sprint has a multitude of packages to choose from that include Sprint TV, Verizon VCast costs $14.99 per month, while Cingular Video is priced at $19.99 per month, with premium packages available as well.

MobiTV was the first comprehensive mobile TV service, and still has the largest selection of offerings of any of the cell-phone-based services. You can subscribe through your cellular carrier. MobiTV has also expanded to offer live TV broadcasts in full-screen mode for laptops, and has partnered with AT&T in its new Broadband TV service, which works with any broadband internet connection. This new service has a 20-channel lineup initially, and costs $19.99 per month. The key limitation is that most of the channels are cable stalwarts, with no broadcast networks yet signed up.

While services like Cingular Video, Sprint TV, and Verizon VCast that put TV on your cell phone will continue to proliferate, we're looking ahead to DVB-H and MediaFLO-enabled handsets, which will receive TV broadcasts on a separate frequency or channel from that of your cellular provider. Cingular et. al. naturally prefer to capture all the revenue from mobile video via their proprietary services, but the fact is that mobile TV broadcasting is a much more efficient way to distribute many channels and stream full-length shows and movies, as compared to the on-demand cell-based services, where each user takes up valuable bandwidth. And with broadcast-enabled handsets, you will not be tied to whatever video your carrier chooses to provide. Look for the DVB-H (digital video broadcast - handheld) or MediaFLO logos on handsets beginning next year. Some mobile TV broadcasts will be paid, but many will be free, another advantage over the typical $20-per-month cost of cellular TV services.