Book reader programs for the iPhone have been around for quite a while now, and it's clear iBooks takes some of the better elements as inspiration. The creator of Delicious Library was actually a bit upset about how closely iBooks resembled his software's interface. But there might just be a giant waiting in the wings to upset Apple's cart -- Microsoft.

Gizmodo, who seems to have an ax to grind against Apple for some reason, brings us possibly bad news for Cupertino by way of this 2009 patent application. Apparently, as part of the killed Courier project, Microsoft filed for a patent for touch-screen based "virtual-page-turn." Here's the money quote as posted by Gizmodo:

"One or more pages are displayed on a touch display...The virtual page turn actively follows the page-turning gesture. The virtual page turn curls a lifted portion of the page to progressively reveal a back side of the page while progressively revealing a front side of a subsequent page. A lifted portion of the page is given an increased transparency that allows the back side of the page to be viewed through the front side of the page."

Microsoft has yet to be awarded this patent, and there have been apps using similar interface technology since at least 2008 (Classics [iTunes link] is a good example), so it's an open question whether Redmond will have any luck. With iBooks being one of Steve Jobs' "tentpoles," it's a good bet Apple's legal department has already found this patent application, considered it, and dismissed it. Time will tell.