In the past I’ve written about using AirPrint on iOS to print to a PDF or a printer connected to your Mac. The process of setting it up was quite a bit of manual work, so I’ve updated the instructions when an alternative became available.
After upgrading to Mountain Lion the printer sharing stopped working and I had to look for an alternative (again). Two easy ways to print and create PDFs from iOS are
In the past I’ve used AirPrint Activator, but have now switched to Printopia for the simple reason that I own a license from MacUpdate Promo. Both tools have a demo so try them for yourself.