Looks as though Amp'd Mobile has filed for bankruptcy. (See story)
This certainly doesn't mean that things are "over" for the MVNO, but it does speak to the high costs associated with operating as a wireless service provider. They've raised over $200M and are publicly reporting 200,000 subscribers. The math isn't so simple though. They are a media company as well as a wireless service provider. Their portal strategy is just getting underway in Japan (KDDI) and Canada (Telus). They've really pushed the envelope with multimedia on the cell phone as well as their UI. Their per subscriber numbers are impressive.