There's more to the world of 3G cards than you might think. For one thing, they may look like mini-PCI cards, but they aren't.

Apparently, they use USB to communicate, and laptops are all built with the ability to accept USB data through their mini-PCI bus connector. That's either something not many people know, or it's something everyone else knew and I only just heard of.

It lets module makers use the same chips on USB dongles as they do in the cards that get built into laptops, according to Larry Zibrik, a marketing director for Sierra Wireless, who briefed me on the company's new fast HSPA modules this week.

Sierra make an awful lot of 3G and 2G cellular cards, and Larry's job is to market the embedded ones, that go to a wider world than just the laptops where I tend to be aware of them. These are what he calls "vertical market" embedded devices, in ATM machines, shop terminals, chunky handhelds for delivery drivers and warehousemen (Sierra supplise both Symbol and Intermec), and all sorts of other "machine-to-machine" (M2M) places. Zibrik tells me there's about 20 million of that sort of connected device out there, and only around 2.6 million 3G datacards and dongles.

Now, most M2M applications are telemetry and are happy with low GPRS data rates, but Zibrik reckons about ten percent of that market is ready to go to 3G. That would make the embedded 3G market about as big as the laptop 3G market - but a lot different in character.

He's got some good - and bad - suggestions for 3G M2M, some of which could happen in the enterprise, or just impact us anyway.

How about DriveCam? It's a the ultimate spy-in-the-cab: a device with two video cameras, that sits by your rear view mirror, filming the road ahead - and filming you. Connected by 3G, it can reveal what actually happened in an incident. Not surprisingly, it's being offered free by some US insurance companies, and is being fitted in taxis, buses and trucks. Surprisingly, I've not met it in the UK - the closest it seems to have got is Ireland.

Or how about field service for routers? Cisco offers 3G cards in its wired devices to provide wired back-up and a remote service option if they go wrong.

Or backhaul for mobile Wi-Fi? Balfour Beatty is putting 3G backhaul on high-speed trains. Somewhat similarly, Becker Marine is using 3G on ships, so they can connect and exchange data whenever they are close enough to shore.

I'm not keen on a drinks machines that plays video, though. We can get spam elsewhere. But it might one day sell tunes and videos to download.