I had the pleasure of doing a basic intro to Social Media APIs session at the Gold Coast Podcamp on Saturday 20th Feb. I tried to make it as basic as possible, but did include some Groovy code that interacted with the Twitter API. Anyway here's the code for anyone that's interested, for groovyists - it's not very idiomatic Groovy code, but I wanted to keep it pretty simple and not use any external libraries.
Follow another user's friends:
Unfollow all your friends
Follow all users that mention a hashtag (can be modified to do replies or mentions)