Looks like the prepaid wireless data market is starting to heat up: Clearwire just launched its Rover service, which offers 4G wireless data for as little as $5 a day -- with two free days included when you first sign up. That's not bad if you just need a quick hit here or there, although you need to pony up $150 for that Rover Puck WiFi hotspot we saw at the FCC last month or $100 for a USB stick, and anything more than a day quickly becomes less of a deal at $20/week and $50/month. Oh, and it's 4G-only, so if you're not living or working in a WiMAX city you're out of luck. Still, those prices aren't terribly out of line with the competition, although we might be more inclined to choose Virgin's $40/mo prepaid MiFi and settle for 3G speeds while getting more coverage. Decisions, decisions -- what a wonderful problem to have.