Mobile broadband has really taken off in the past few years, with all the major providers getting in on the act.
Having a broadband connection wherever you are is a great idea; it saves you the pain of finding a wireless hotspot, and basically enables you to work anywhere.
That's the theory at least. In many cases, speeds are slow and coverage patchy. However, faster and faster mobile broadband offerings are appearing all the time, and the latest such offering is from Virgin Mobile.