F.C.C. Weighs Plan to Warn of High Cellphone Bill (nytimes.com)

"The Federal Communications Commission said Tuesday that was seeking public comment on a plan that would require wireless phone companies to notify customers when they are running up unusually high charges for data usage, roaming or other uses beyond what is covered by regular monthly fees."

Why stop there? A "minutes meter" at the bottom of your screen could keep you aware of what you're using. Clicking could give you detailed reports, rollover minutes remaining, etc.

Unless of course, they're making money by keeping you in the dark and surprising you. But they wouldn't do that, would they?