I've been building out a complete RDS environment (RD Gateway, RD Web Access, RD Connection Broker, RD Session Host). I've been testing the environment with a couple of test accounts that mimic a typical user account (similar security groups). Printer redirection is working fine for the test user account on both internal and external networks.
It wasn't until I asked a real user to log in for me to find that their printers are not being redirected. I logged in as myself (I have domain and local admin rights) and printers are not being redirected for me either. When I used the test account to log in on the same client PC, printer redirection worked. Thus, I don't believe it's a problem on the user's PC. This is for both external and internal networks (using RD Gateway for ext, and Connection Broker for int).
RDS Environment is running Windows 2008 R2 SP1, clients are all Windows 7 Enterprise SP1.