Social networking site Facebook has made the first acquisition in its three year history – a small start-up called Parakey whose software is still in development.

The purchase looks set to boost its recently launched open source strategy – Parakey is run by Blake Ross and Joe Hewitt, two techies best known for helping to create the Firefox web browser.

Both will both go to work for Facebook as part of the move, while Parakey’s software will also be folded into the company. We think this acquisition is about the talent first, and the software second.

Parakey has been developing a platform for web applications to be accessed from users’ desktops. Om Malik said “it wouldn’t be a surprise” if Facebook offered an offline version of its service to members following the move. He also saw the acquisition as part of a plan by the site to “buy all talent under 25 in the Palo Alto-Mountain View area”.

Facebook founder Mark Zuckerberg, meanwhile, told the FT that the acquisition “fits in with” the site’s open source model:

“Blake and Joe built the Firefox web browser and then turned to the developer community to build on top of the foundation they’d established, not unlike what we’ve done with Facebook Platform.

“The work they’ve done with Firefox and Parakey and their approach to building products fit right in at Facebook.”

Facebook decided in May to open up to third party developers - giving software producers an opportunity to target its 30m-strong audience while improving its offering to members.

Recent figures have shown that the site is catching up with rivals Myspace and Bebo in the UK.