Yes and No. At present only a handful of new printers on the market natively support the iPad's AirPrint feature (where you are able to use the print function within an app).
As the previous poster mentioned, it is possible to set up a Mac so that it shares an attached printer via AirPrint with your iPad -- the downside is that you still need a host computer running as a print server. You're really doing just host-based printer sharing instead of directly talking to a networked printer.
Finally, there *are* a few printing apps that actually communicate directly with networked printers or external print server appliances. The two downsides of this approach is that the app must have support for your specific printer, and more significantly, you have to do all your printing from within the app itself -- you cannot just hit the Print button in any arbitrary app and expect it to work (I'd happily admit to being wrong about this if anyone has any direct evidence to the contrary).
[Fwiw, I use an app called ePrint to do LPR printing to an external print server attached to ancient HP Laserjet. A bit slow, but it works.]