I think it's especially important that Virgin Mobile resolves this, since the market share is basically theirs for the taking.
Their basic $35/mo. plan, which includes text and data, is great for my needs, so I called AT&T and told them I was thinking of switching, but because I'd been an AT&T customer for years, I was giving them a chance to match that kind of offer. Not only did the rep basically say, "Nope, we can't come close to matching that," but -- more surprisingly -- he had no script to say, "Here's why you shouldn't switch to Virgin." Which says to me that AT&T isn't taking Virgin seriously yet.
If Virgin Mobile can get its account security act together, I think it can make pretty good in-roads against the bigger carriers.