If you're doing it to get department unity, or to get better visibility for your people so you can get the recognition for a good job, it's not a terrible idea. The trick is that you don't want the IT guys to dislike it, or so that users don't start pulling guys away from higher priority tasks due to the new visibility.
I know, I prefer wearing the uniform when I go out on calls (saves me from having to think about my outfit), but our shirts are actually comfortable and appropriate for the weather and clients we're servicing. That and as a small company, we really need to have a professional, unified image.
Having an internal team wear them just to be easier to stick out, or for reasons that don't help your team directly, will brew internal tension.