New Twitter use is a prime target for infections. If your employees use twitter with or without your approval you will soon be at risk. Here is a near miss example.
A new way to cause mischief quickly spread through short-messaging service Twitter on Tuesday morning before the site could fix the problem, as mysterious "tweets" of blocked-out text propagated themselves and caused pop-up windows to open.
http://localtechwire.com/business/local_tech_wire/news/blogpost/8329017/