how does facebook's new friend sorting algorithm work?

[Dread]

I noticed that my friends have become quite a bit more static on my friend's list. Every time I go there, it is still the same people in the same order, occasionally with one person jumping up in the list.
I notice that the chat also seems to sort itself, but it seems to be much more dynamic and work on several more parameters, such as who you have talked to most recently.

So, does anyone know how these sorts are intended to work, and on what parameters?

[WK of Angmar]

The sorts are probably very complex and they are done server-side, so as far as I am aware, there is no definite answer to this, but it would be possible to have a good guess.

This link seems good: http://www.quora.com/What-algorithm-is-u...ofile-page
As does this: http://ask.metafilter.com/215797/What-is...-algorithm