Lately my inbox has been overrun with spam.  It is always a message from someone I know with "no subeject" in the subject line.  The the email is a link to some wordpres.us website that actually redirects to a spammy site (advertising the usual spammy stuff like viagra, etc).  The url of the bogus blog often has the person's name in it.

It seems someone out there has created a system that hacks email accounts and creates spammy blogs automatically.  Probably some kind of malware or worm.

I'm not sure what precautions you should be taking other than keeping your anti-virus software updated.