I was asked an interesting question earlier this week. Paraphrased:
With the sheer number of people using semi-proprietary closed systems such as Facebook or Myspace for their personal and business communication, might they be serious contenders for a real spam solution?
Some time ago, I wrote about the, "People are stopping using email" meme. I said then that it's not so much that people are turning their backs on email as a medium, but that they have a wider choice of media available to them now -- such as IM, SMS, and social network websites. They're just more likely to choose the medium best suited to the task. Nothing's changed my mind since then.
Having said that, feel free to
poke me,
follow me,
LinkIn, or
whatever.
To paraphrase
Meng Weng Wong's recent curry-inspired trendmap, all such media attract spammers if they become sufficiently popular. Lest we forget, spam was first a big problem on USENET -- email came later.
"...particularly if you're interested in spam, malware and the like"
Oh dear. 
As you may know, every day I write the IT Blogwatch column for Computerworld. The idea is to take an IT/tech news story from the past couple of days, and tell the world what bloggers are saying about it.