I'm searching for a printer with the following characteristics:
- network support (e.g. 10/100 Mbit)
- duplex unit
- above features must work on Ubuntu 10.04 out of the box (<< that's why I'm asking here)
I can't say for certain, but in my experience, the HP line color laserjets have the best linux support. Specifically the 4600/4650 series that I have experience with. You'll probably want the hplip package, which I believe is in the Ubuntu repos.