The last Paralympics was shown in the US on Universal Sports, which I think now is just NBC Sports or whatever they call it. I would guess they will show at least some of the events there. I’ll watch the same events if I happen to catch them as I did for the Olympics, which would be mostly swimming.
Universal Sports is a different channel from NBC Sports Network (which used to be Versus, and I think Outdoor Life Network before that). It may be its own channel now, but at one point, it was only available as a digital subchannel on NBC stations (which meant, among other things, that AT&T U-Verse refuses to carry it under its “we don’t carry subchannels” policy).
As for 2012, most of the coverage will be online. However, NBC Sports Network will have four one-hour shows (September 4, 5, 6, and 11, at 7 PM Eastern), and NBC will have a single 90-minute show covering the whole thing on September 16 at 2 PM Eastern. (The 90-minute show is how NBC usually covers the event; I remember the one from 2004.)
The online coverage will be on the “U.S. Paralympics” YouTube channel, consisting of 10 “video highlights packages” each day, as well as at USParaylmpics.org.