Yahoo mail servers appear to be infected with some kind of weird virus. It's sending out emails titled, "(Whoever) sent you a message from a friend" and asks you to click a link. I've already received two from different people. If you get one from me, delete it. I'm not sending out links and I haven't managed to answer any emails in weeks, much less send new ones.
Also, if you do the social networks, a reminder that Facebook and My Space is also being hit with a similar bug.