When I think of handheld computer, I think of Nokia's IT series, the OQO computers, and Sony's UX series. The IT is the only one of the three without cellular internet... I think "does it have integrated WWAN?" is a perfectly reasonable thing to look at when considering a handheld computer.
wireless & networking * Wireless LAN: Atheros tri-mode 802.11a/b/g with diversity * Bluetooth technology: Integrated Bluetooth 2.0 with EDR * Ethernet protocol: VGA/Ethernet adapter (included)