Indeed, Apple gave that rear camera a fairly meager resolution, prompting some to suspect it was included just so competitors couldn’t use its absence as a selling point against the iPad.

However, one developer may have found something decent to do with that rear camera. Levity Novelty has released an app called Invisibility that uses the combination of the rear camera and the iPad 2′s gyroscope to create a cool illusion of invisibility. The 99-cent app can take a picture of a table top and then be used to pan over that same table top, making the tablet appear to be transparent.

“The iPad has always promised it is a magical device,” Levity’s David Levitt said in a telephone interview. “Invisibility is delivering on that promise at a whole new level.”

Another developer, Total Immersion, has come up with Magic Mirror, a clever use for that front iPad camera that lets users “try on” various outfits, hairdos and accessories.

Levitt said his app has been in the works since the debut of the gyroscope-equipped iPhone 4, but said he shifted plans to the iPad 2 when it was released in March, offering a preview version of the app in April before delivering the final app this week, with a few more tricks.

Levitt said Invisibility combines a few of his passions. He said he has been working on virtual reality technology since the 1990s, when it took dual $100,000 Silicon Graphics workstations (one for each eye) to achieve realistic effects.

His app got a boost on Thursday when Wired writer Steven Levy tweeted that the app was “the coolest use for iPad 2 camera I’ve seen to date.”

“Thank you, Steven,” said a happy Levitt, who noted he brought an early version of the app to one of Levy’s recent book signings.

“It’s this wonderfully distracting, conversation-starting thing,” he said of the app.

Levitt said he plans to bring the app to the iPhone 4 and the latest iPod touch, but said it will remain an Apple-only app for now.

“In a way, we are an Apple-only shop partly because the other platforms don’t consistently have gyroscopes or an API for them,” he said. “It’s just a natural for us to stick with that, but obviously that could change.”