• To reduce costs. Banks hope to reduce calls to customer-service representatives for basic account information, like checking balances. The savings can be dramatic: While a chat with a phone rep costs the bank about $1 per minute, Gillen said, a one-way text costs just 3 cents.

• To improve fraud prevention. Mobile banking can allow banks to quickly notify customers of potentially fraudulent transactions and get a customer's OK before proceeding. Contacting customers via text or e-mail is cheaper than using call centers, and response times may be faster than when banks call a customer's land line.

• To trap you more firmly in their web of services. With the onset of electronic banking services, banks realized something interesting: The more technological services a customer adopts, the more likely he or she is to stay with the bank. If you use direct deposit, automatic debit and/or online bill payment, you understand this intuitively: It would be a major hassle to change banks. Adding mobile banking improves such "stickiness."

• To boost fee income down the line. Banks typically don't charge for mobile-banking access, but they hope to get a slice of the next step in mobile banking -- using your cell to make purchases.

Citibank is already experimenting with mobile payments. In one trial, the bank has partnered with MasterCard, AT&T and Nokia to put chips in Nokia phones that allow customers to make debit and credit card purchases by waving the phone at special point-of-sale devices at certain stores. In another pilot, Citi has partnered with Obopay to allow customers to send and receive money using any mobile phone.

That sounds pretty cool, but banks will still need to reassure customers that such transactions are safe. When Javelin polled consumers about whether they might try mobile banking, fully one-third said it sounded "too risky." Seven out of 10 worried that their personal information could be more easily obtained if their phone were lost or stolen, while 62% worried that their account could be compromised by hackers, spyware and viruses.

As I said earlier, there's currently not much risk, because:

• What you can do on your phone is pretty limited.

• Your account number typically isn't exposed; during the sign-up process, the bank "authenticates" your phone so you can use it to access your account without typing in the number.

• Hackers, virus writers and other bad guys are more interested in attacking your computer than your phone.

Right now, most malware and hacking attacks on mobile phones are more in the "nuisance" category than the real threat category. A bad guy might lock up your phone, plant a picture of a skull and crossbones on your screen or trick you into calling expensive 900 numbers.

Hackers are just getting started

That was pretty much the level of tomfoolery Web surfers encountered before e-commerce really took off, Egan warned. Once financial transactions soared, phishing, pharming and other far more sophisticated threats took over. He expects the same progression as more people adopt mobile banking and do more with it.

"Thieves always follow the money," Egan said. "Thieves followed the money to the desktop (computer) and they'll follow the money here."

Egan worries that banks will be too slow-moving to react to the evolving risks. Already, he said, many are overly confident that their recent efforts to boost online banking security will translate easily into knowing how to thwart mobile threats.

For now, here's what you need to know if you want to try out your bank's mobile capabilities:

• If available, try the browser-based version first. "Walk before you run," advises Egan. Browser-based applications are fairly simple to set up and use, while offering decent encryption.

• Don't store your user ID or password on your phone. Or at least tuck the information behind the extra security offered by add-on programs such as JSJ Wallet for Treos.

• If you can, download, update and use antivirus software on your Web-enabled phone. Antivirus products only are available for phones using Microsoft or Palm software, Egan said, and even then some users will run into problems trying to install security software on corporate phones.

• Ask what protections your bank offers against fraud. Some banks, including Wells Fargo, offer guarantees to their customers that they'll be made whole if they're defrauded because they used online or mobile banking.

• Shut down a lost or stolen phone account immediately. If you do lose a mobile-enabled device, your first call should be to your carrier to shut down service and your second to your bank to disable the mobile connection.

• Through a phone's Web browser. Nearly all cell phones sold these days come with a browser, and the browser's WAP 2.0 security is pretty good, Egan said. But unless you have a phone with a keyboard, mobile banking is a bit cumbersome. Also, data charges on a cell phone can add up fast. If you don't already have one, you'll need to buy a data plan, which typically adds $30 or more to your monthly bill.

• Through a bank-specific application. This is something that's either already part of the phone you buy (preloaded) or that you get from your bank's Web site (downloadable). Again, you'll need a data plan. The download process can be difficult for a novice to navigate, although once enabled, accessing your bank is easier and faster than with a browser-based version.
• Via text messaging. Even old phones without browsers can send and receive texts, so this widens the potential banking audience considerably. But text messages typically aren't encrypted, and the functions you can perform are limited. Instead of one session, you might have a lot of back-and-forth texting to get the information you need.