There is a handler within Active Social. You can call something like this:
height="80" width="80" class="profilepic" src="http://www.yoursite.com/desktopmodules/activesocial/profilepic.ashx?portalid=0&uid=USERID&h=80&w=80" alt="" />
Where USERID is the userid of the member you're trying to show and h and w are the height and width of the photo.
I haven't tried to access it pro grammatically but theoretically it's part of the DNN user profile so it should be accessible through membership