Screenshot courtesy of Canon, Inc.
Have an iPhone and a Canon PIXMA printer with WiFi interface (MP990, MP640, or MP560)? If so, Canon has a free iPhone app that lets you print photos directly from the iPhone to these printers…
Canon Easy=PhotoPrint for iPhone 1.0.0 (iTunes App Store)
The app supports a wide variety of paper sizes and types (plain and various photo papers). Multiple photos can be selected for printing. And, up to 20 copies of a photo can be printed.
This all sounds good, right? Unfortunately, the app has a mere 2 star (out of 5) rating from the 18 people who have rated it so far. 12 of the 18 reviewers gave it a single star.