SegmentedControl is a project mainly written in ..., it's free.
A Radio group styled to look like Segmented buttons
http://www.androidpatterns.com/uap_pattern/segmented-control says :
"A segmented control is a horizontally aligned set of segments, containing 2-5 buttons, that act as filters on a set of data by selecting them."
Isn't it just a Radio group styled differently? So is this.
Check out the screenshots and browse thru the drawables (courtesy naz).