Litan is more conservative. She wouldn't use a mobile phone's browser for banking, she said, because she doesn't think mobile browsers are secure enough. And she's distrustful of smart-phone apps that aren't vetted in advance. Apps for Android, BlackBerry and Windows Mobile phones are "open market," which means third-party software isn't evaluated and approved by the phones' makers before being released. By contrast, iPhone apps are tightly controlled by Apple.

Such controls don't guarantee absolute security, as the bank app mess last year clearly shows. But they improve your odds of avoiding serious problems, Litan said.

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"This is a very politically incorrect thing to say, but if you want to do financial services (from your phone), go out and get an iPhone," Litan said. "From a security standpoint, you want to go with the most closed environment."

Liz Weston is the Web's most-read personal-finance writer. She is the author of several books, most recently "The 10 Commandments of Money: Survive and Thrive in the New Economy" (find it on Bing). Weston's award-winning columns appear every Monday and Thursday, exclusively on MSN Money. Join the conversation and send in your financial questions on Liz Weston's Facebook fan page.