We, PRO-SYS, do perform quite a bit of remote work. In fact, we've done remote work (from Vancouver/Calgary, Canada) to Toronto (Canada), many states, and even some out of the country work. With Citrix, or other Telnet-like, connections it relatively easy to connect to their working environment.
The problem is finding the clients who are okay with this. Initially, some clients will enter into small projects to determine how well the relationship will work. Sometimes you will meet their expectations, other times it doesn't work so well.