First you need to be clear on what the printer needs to be compatible with. It's an important distinction that printer drivers need to be compatible with the Operating System, since I do not know if you are running Windows NT4 TSE or Windows 2000. In future, we have .NET, Windows 2003 or whatever it's going to be called.
The main issues in the past have been due to printer driver name mismatches between other O/Ses (Win9x mainly) and NT versions.
There is a list of drivers on Hewlett Packard's site that are certified compatible with Terminal Services, so you should be safe with one of these. Unfortunately other manufacturers do not seem to provide such charts, so cast-iron guarantees cannot be made.
Having said that, the Lexmark Optra series seem to work well - one of the first colour printers I hooked up to a MetaFrame farm was a Colour laser - 1250, I think.
Hope this helps CitrixEngineer@yahoo.co.uk