not extremly new, but there are some RCE concerns on the Skype application might interest us reversers

http://www.mathaba.net/MNN/www.skype-news.com/zAnalysisCorp.pdf

There's a lot of rumors around this paper nowadays, a discussion here would be interesting..

That's a cool paper. It's possible that you could get free calls (or perhaps charged to someone else) to POTS usking skype by exploiting some flaw in their protocol.