GPS units get smaller and smaller, and here's an example—the Acer e310, a 4-inch-tall GPS device that runs on Microsoft Windows CE. About the size of an iPod, its 2.8-inch 320x240 touchscreen just about fills up the front of the thing, and in addition to its GPS navigation duties it also functions as an MP3 player, photo viewer and address book.
Too bad there's no flash memory slot
(see correction below). It's said to deliver four hours of navigation time or eight hours of other uses such as playing music. Now if these GPS functions could be incorporated into every cellphone, our interest would be piqued. No release date or pricing was set.
Update: Thanks, Martin, for translating the company's German site, and letting us know the Acer e310 does have an SD/MMC memory slot!
Acer e310 GPS [MobileWhack]