I ran my entire farm via a Virgin Mobile 3g connection (as well as the entire rest of my network) for 2-3 years - had to use a Win machine with connection sharing as I could never find a LINUX-based solution that would work, so I fed the shared connection from that machine into my LINUX router/firewall/gateway machine.
Latency and throughput on that connection were JUNK, but it worked (I saw perhaps 0.5-1% higher orphan/stale share rate vs a good connection).
I've seen mention of routers/hotspots that would work directly with such a dongle/aircard, but since ALL of them I ever found were WiFI and I don't do WiFi that wasn't an option for me.
Any idea how much data was downloaded/uploaded on that 3G connection? Some providers have data caps, so it's important to have an unlimited plan...