According to TrendLabs, there is a new Koobface component that makes Internet Explorer create Facebook accounts. It automates the whole process - the browser registers the account, confirms and activates the registration via Gmail, joins random Facebook groups, adds friends, posts messages to their walls...
Another "smart" Koobface feature is that after it has created the account, it makes sure not to surpass the maximum number of friend requests allowed by Facebook, so it doesn't raise the suspicions of its administrators.
The messages that the account posts on friends' walls usually has a link that, if clicked, takes the unsuspecting user to a site that hosts the Koobface loader.