I've been getting that particular spam from other people's hacked accounts for about a month now, most point to an online pharmacy. It was clearly spam, and you clearly didn't want to click on the tracking link that would probably install something on your pc, hijack your address book, and do it all over again. I did a google search on it when I noticed it was happening (I started getting email from people I hadn't heard from in years and it all had one line with a link in it...) and this site answered what it was for me so i didn't have to click on the link myself:
http://answers.yahoo.com/question/index?qid=20100912075430AAOFbYi and thought nothing more of it. And then one of my email accounts got hijacked.
I hadn't opened the spam link, I had deleted everything, and the account that was hijacked was a gmail account that I haven't used in over a year. When I received an email from "myself" I got suspicious, and logged in, and gmail told me my account had been compromised. Again, I have no idea how it could have happened, as I don't use the account much anymore.
So I changed all the passwords on all of my email accounts. I hope that takes care of it.