• by Mark Walsh  @markfwal, May 28, 2010

With Android rapidly spreading across mobile phones, it only makes sense that Facebook would want to give developers tools to incorporate its social features into applications for the Google platform.

To that end, the social network has released a software development kit for Android that will give app creators access to Facebook's Graph API (application programming interface) as well as the ability to authenticate users and enable posting of updates back to Facebook.

The move comes as Android is gaining ground as a smartphone operating system. A report from NPD Group earlier this month found that sales of phones running Android in the first quarter had outpaced the iPhone for the first time, with a 28% share of the U.S. smartphone market compared to the iPhone's 21%.

Google CEO Eric Schmidt also said this month that the company is now activating 100,000 Android phones a day, up from 65,000 at the start of the year. There are also some 60 different Android models available across different handset makers and carriers, with the HTC Incredible being the most high-profile new addition.

After launching a developer kit for the iPhone more than a year ago, it's clear that Facebook has caught onto the rise of Android. Earlier this year, Facebook hired Erick Tseng, formerly senior product manager on Google's Android mobile operating system, as its new head of mobile products.

Facebook says that more than 100 million people worldwide use one of its mobile products, the latest of which is O.facebook.com, a stripped-down version of its service aimed at users in emerging markets.