From this Washington Post article:

Internet spammers launched a widespread attack on e-mail inboxes this month. But instead of trying to lure users into opening a corrupted attachment, they’re concealing a computer virus in a link to an online greeting card.

In most cases, the subject line informs recipients that they’ve received a greeting card or a postcard from a “friend,” “family member,” “worshipper,” “school-mate” or “neighbour.” When the e-mail is opened, there’s a link to a Web site that uploads a virus to the recipient’s computer.

I’ve received about 40 of them over the last week.