Never mind hackers. Beware the taxi cab. A new survey says about 12,000 electronic devices - no doubt many of them unsecured - were left behind in taxis during a six-month period earlier this year in the San Francisco-Oakland Bay and Washington, DC-Baltimore areas.

Pointsec Mobile Technologies , the mobile security company that commissioned the survey, said the big numbers might seem surprising in light of the many high-profile data breeches that have been publicised this year, but that losing such devices now has to be considered a fact of life. The question is how companies go about protecting data when such device losses occur.

The survey of 85 taxi companies found that about three-quarters of the lost devices were mobile phones and that about two-thirds of them were lost in the Washington, DC-Baltimore area. About 80 percent of the phones were eventually returned to their owners in the Washington, DC area, while about 65 percent were claimed in the San Francisco area.

PDAs were also left behind often, with 2,260 lost in the Washington, DC area and 306 in the San Francisco area. A higher percentage of these devices were reclaimed than mobile phones.

About 350 laptops were lost between the two areas and all were returned to the owners. Of course, getting the devices back doesn't mean that the data on them wasn't compromised, Pointsec points out.

The results from the US were part of a global survey of 2,000 cab companies. Among the more shocking numbers: Londoners forgot 54,874 mobile phones (over two per taxi) during a six-month period earlier this year.