I have tried to post this to the HCL, but am havung trouble with this board.
There is now a driver for the HP Color Laserjet 2600n, which works with CUPS.
I am currently running kubuntu 6.06 (Dapper) with all the updates.
I managed to get the printer working by following the instructions from Rick Richardson on this site:
I could not get it to work with the USB connection, so I set up the printer as a networked printer, with a fixed IP address and plugged it into my router.
CUPS found it and installed it, using the driver "HP Colour LaserJet 2600N foo2hp".
The quality is not as good as some deskjet ink printers (picture are a bit "dotty" - like a colour picture in a newspaper), but I am very happy with it.
Many aspects of the printer can be interrogated / changed by accessing the printers built-in webserver at http://addy.of.the.printer