In response to a blog here by Lisa:

Facebook did technically have the "Friend Updates" system in place far before MySpace and further Facebook allows you to track all changes in you friends network and does not limit you to a set amount as is the case with MySpace.

I do not necessarily believe at this point and time that Facebook is outgrowing MySpace in total Unique users but I do believe Facebook's active user base is increasing and that the playing field is slowly but surely leveling out between these two giants.

Thanks to Lisa for pointing this out although I was aware of Facebook's friend update feature I just forgot to give Facebook the proper credit for possibly being the originator of this idea. Feel free to visit Lisa's blog at http://lisamcconrad.wordpress.com. I will continue to track Lisa's blog and consider it for addition to my BlogRoll.