3G Wireless Mobile Phone data network accesss for PDAs

Many PDAs such as the newly announced Nokia 810 Internet tablet are not cell phones...that is it does not include the necessary radio transmitter/receiver chips required to connect to the cell phone networks. These PDAs rely on Wi-Fi for Internet access.

However often WiFi is not available. Far more ubiquitous ...at least at this moment... are the cellular networks that carry voice and data.

In this case a USB or SDIO form factor 'modem' card would be useful and desirable. (Of course, an appropriate cellphone with the capacity to be connected ...often by Bluetooth...can be used easily and readily as a modem but its a cumbersome two piece solution.)

The iPhone and other PDA phones solve this readily because they have both Wifi radios and cellular radios but I like the idea of a PDA with a cellular network card.

The PDA requires no carrier contract...most of the time peer to peer Internet-based voice is available though Skype, for example, ...is often slightly larger with therefore a much better screen. Of course a cellular data card will require a data contract with a carrier...but somehow that seems less of a burden than the contracts required by AT&T for example.

Here is an example of a USB form factor implementation but its a very awkward implementation: http://www.jiwire.com/sprint-u720-usb-modem-product-overview.htm

Its really no advantage from a cell phone tethered by cable or connected by bluetooth and therefore wireless.

I looking for an sdio form factor radio with all the circuitry contained within the sd card form..maybe this is impossible given the antenna requirements but I've read of them I'm sure. I just at the moment cannot locate a supplier or find Linux drivers.

Here is a reference to existing SDIO cards.

Here is an example of CFIO cellular modem. An SDIO 3G modem shouldn't be far away.