You're probably already aware that spammy malicious links can be fairly prevalent on Facebook's walls and in its messaging system. In order to try to mitigate the problems caused by such links, Facebook has teamed up with Websense Inc., a web security firm. The new partnership will mean that when a Facebook user clicks a link (this is all explained in the infographic above), that link will be checked against Websense's giant database (or, as they refer to it, a "classification engine") of known malicious links. If everything checks out, the user will simply proceed, but if the link is flagged, a new page will open asking the user how to proceed.
Many websites make use of anti-spam tools such as this, but until now, Facebook's had almost no protection for users against such attacks, and people have shown themselves to be willing to click almost anything. In the video below, you can watch Websense's CTO explain how the partnership will work.