Over the past few days I've received about 10 follows from various people in Twitter. I found it strange when reviewing their past Tweets all had the same single tweet. I was getting suspicious and then today I got a follow from someone I knew (and followed), but the Twitter ID looked different.
Upon checking out the Twitter account I knew it wasn't him. So I decided I was going to investigate and write a detailed post about it. During my investigation I came across this blog post which details the problem in great detail http://news.cnet.com/8301-13515_3-10146731-26.html.
So be aware that like all good technology Twitter is being exploited by those who want to trick us to make a buck.