Facebook today rolled out one of its most significant features yet – ‘Friend Lists‘. Yes, it is now possible to organize your friends into different groups. This feature is great for easily messaging larger groups in Facebook, sending out invitations, and most significantly: filtering updates to only show to select groups.

Nick O’Neil of allfacebook calls this Facebook’s “Killer Feature” – and it very well could be for those potential users – such as business users – who were wary of signing up for a network once dominated by college kids. Inside Facebook notes that this will also greatly help those users such as Mark Cuban who have reached their 5,000 friend limit give some structure to their massive friend lists.

When Facebook first pre-announced this feature in September, I, like most everyone thought it was a great idea for competing with the likes of LinkedIn. However I also assumed they would have set options such as a ‘Work Contact’, ‘School Contacts’, etc. The fact that you can completely customize these lists, making as many as you want and still use them to filter who sees what data is even better than I imagined it would be. I see myself being a lot less hesitant to not only update certain things on Facebook, but add certain contacts as well.

I used to be all for keeping my social networks separate by way of one account on Facebook and one on LinkedIn, but with ‘Friend Lists’ I’m not sure how necessary having both is anymore. It is after all easier to have one de-facto network with which to update and be updated from. If other users feel the same way, LinkedIn could start feeling some heat…