I just saw this dedicated AirPrint daughter board, so I thought I would repost some info I found on network printing with the iPad. I hope it helps.
I trolling over at ModMyI, and came across this post from one of their members. My boss has been going buggy because he can't print from his iPad, so I've been keeping an eye out.
Now, I'm not tech head, but if I follow this right, you can print to all networked printer this way from you iPad.
Mac users go here:
High Caffeine Content: Return AirPrint sharing to Mac OS X v10.6.5
AirPrint Hacktivator Netputing
Win Users go here:
How to Install AirPrint to Enable Wireless Printing on Windows? | Jaxov
The original post from ModMyI is here.
Hacktivate AirPrint on Mac, Windows Shared Printers
I hope this helps! I'll be using it when I get my iPad (22 days & counting!)