I worked in a place where devs were also top-tier tech support. This worked well, as we got to figure out what the problems were, got to help teach our users the capabilities of the system, and got to look cool when we fixed a problem in 2 minutes. This was for an in-house network appliance, so our users were pretty technical anyway, which definately helped. What did not help tho, was when the help desk got lazy and started directing tickets to us which had no place in our laps. Then it all went down hill.

In short, its balancing act.