Nick Bilton at The New York Times reports Facebook is in the final stages of testing its first official iPad application, which should launch in the App Store for free in the coming weeks. The lack of an official Facebook app for the tablet contributed to the rise of third-party solutions in the past year that were nothing but redesigned versions of Facebook’s website wrapped inside the iPad’s screen; according to The New York Times, Facebook’s iPad app has been carefully designed and tested by Mark Zuckerberg himself to ensure the quality of the product and a great Facebook experience on the tablet. For instance, the app will sport chat and Groups integration and will allow users to upload photos shot with the iPad’s cameras. Or, users will be able to browse photos in full-screen in a completely new, beautiful Facebook UI.

People briefed on Facebook’s plans say that in coming weeks the company plans to introduce a free iPad application that has been carefully designed and optimized for the tablet.

The app has been in production at Facebook for almost a year, going through several design iterations, and is now in the final stages of testing, according to these people, who declined to be named because they were discussing confidential product plans.

With more than 600 million Facebook users out there and 25 million iPads sold since April 2010, the potential for adoption is huge. There’s been some talks lately as to whether Facebook is really planning to launch an HTML5-based development platform to take on Apple’s Mobile Safari, and indeed The New York Times is also reporting Facebook will launch a new version of the regular website for the iPad’s browser. It’s unclear when all this will launch (NYT says the iPad app will be available in the “coming weeks”), but it’s safe to assume the new website won’t offer as many features as a native app. The Facebook app for iPhone has been around since 2008 and it’s the most popular free App Store download of all time.