According to The Boy Genius Report sources, evidence suggesting that Apple is hard at work on new iPhones and iPod touch devices can be found in the just announced iPhone 3.0 firmware (currently available as a beta). Even more interesting is the fact that there appear to be up to six future devices coming.
Buried in the iPhone OS 3.0 restore ramdisk are references to an iPhone 2,1 (already found in an earlier firmware), an iPhone 3,1 and an iPod 2,2 and iPod 3,1. Then there are two more mysterious entries: iProd0,1 and iFPGA. To date, Apple has used the first number to mark major revisions and the second number for more minor ones. If this naming convention is still in effect, it appears that two major iPhone updates are on their way as well as a new touch update.
Only time will tell if these are actually pointers for new devices but it does suggest that Apple is looking to expand its reach into the mobile space with new models and even new form factors (maybe a netbook with a touchscreen and 3G connectivity).