Remember Virgin Mobile? Sure you do -- not long ago the last-man-standing MVNO snapped up Helio, and seemed ready to take its place as one of the few boutique prepaid operations still er, operating. Well that appears to be all but done and done, as Sprint has just announced a "definitive agreement" to purchase the company for $483 million in sweet, succulent cash (which looks to be right about what it was worth to begin with). It looks like Sprint
