2 year contract; they do offer some plans without contracts, but not the data-only. Not sure on devices they offer, as I'm currently looking at getting $30 voice (cheapest available) with the $6 data; I assume you can get the contract (with full subsidy cost built-in ) and not buy a subsidized device, in which case any unlocked GSM-1900/850 (with EDGE) should do. VoIP is said to work OK over EDGE; I'll know once I have it. Latency is not so hot, but that's something VoIP tends to suffer anyway, so I'm used to it. And tethering is allowed, although they don't offer support for it; no worries about getting the boot because they caught your usage patterns.

I realize it's quite possible they choke back on things, or raise rates exorbitantly, as they get 3g out there. But I'm not writing them off. (Oh, and roaming onto AT&T's network (and some others) is free, provided your phone has the 850MHz band, as most current offerings do; coverage is therefore not much of an issue.)

Of the US carriers, they look the most promising from here; that's why I'm looking at switching to them. I am well aware of the possibilities for things to go bad, but I guess I just haven't been burned often enough.