airprint is pretty cool. On my Mac and PC I could setup a separate profile to use my color printer in black&white mode. Is it possible to do the same when using air print from iphone/ipad?
The built-in AirPrint doesn't allow this sort of functionality as of iOS 4, but if you get the HP ePrint app, you should be able to do B&W printing and manage other settings. This of course only works if you have an AirPrint/ePrint HP printer, it won't work with any other printer that you've hacked to set up with AirPrint.
Printopia for Mac will let you configure what settings the printer will use when you AirPrint. For example, you can select to use B&W only.