There has never been a driver for the 2600n as I've always had to download it form HP. Outside of that, every single time I've installed 10.6 it's been great.
I've upgraded about 30 computers to Snow Leopard, most of them upgrade installs. I may redo them with a clean install at some point because I've discovered that the upgrade installs are slightly sluggish. Still MUCH faster than Leopard, just not as fast as the clean install Snow Leopards.
The only issues I've had so far other than inconsequential glitches are:
1) Growl is buggy on Snow Leopard. I had to delete it from my machines. I understand a SL version is nearly ready.
2) VueScan would crash on load, but they immediately released an update that took care of the problem.
These couple of Snow Leopard bugs are so worth all the Leopard bugs that are now gone.