Linux, which has been gaining momentum in the enterprise, has not become nearly as popular with handheld devices. In 2002, Linux was used on 1.7% of PDAs. In 2003, that number is expected to grow to 3.7%, according to the Framingham, Mass.-based research firm International Data Corp. While a pocket Linux PDA may never hit the market with any force, Linux is making surprising strides on other mobile devices, enough to cause concern at smart phone operating systems market leader Symbian Ltd., said IDC analyst Kevin Burden. Burden told SearchMobileComputing.com where Linux is -- and isn't -- likely to become a wireless force.