If you're a LinkedIn user, you should probably be aware of this.
Around 10,000 LinkedIn users are targeted in a scam to trick them into opening messages that contained a malicious file that was being portrayed as a list of business contacts. The sender's email address was spoofed to make it look like it was coming from email@example.com.
The naughty software attached to the file was a typical piece of malware that attempted to harvest passwords, user names, and other sensitive items from the user's computer.
You can read Brian Krebs full blog entry to get all the dirty details, including examples of the emails. And remember - never open an email or file that you weren't expecting to receive, and never turn on the preview pane feature of your email client, like Outlook, Outlook Express, Thunderbird, etc.