Just wanted to report success in using an Alix 6F2 board fitted with a Mini-PCI-Express 3G radio card (Novatel EU850D miniPCIe). http://shop.varia-store.com/product_info.php?info=p1204_UMTS---3G-Zeroshell-ready-system-with-ALIX-6F2-and-accessories.html
The only small issue is that the SIM card has to go in the SIM card slot on the Novatel card. It doesn't work in the SIM card slot on the motherboard / front panel. Perhaps there's an AT init string that tells the Novatel card to read the SIM card slot on the motherboard.
For UK users needing SIM cards with routed static IP blocks (for No-NAT mode), I can recommend www.aaisp.net
(I have no connection to them other than as a happy customer).