&#62;<i>It seems sensible to assume it helps them for something otherwise why bother developing and releasing it?</i><p>Well surely the proof is in the eating - that is, if they've implemented it then it clearly works, they wouldn't be stupid enough to implement it if it's going to cost them money.<p>To answer your [rhetorical] question: The cost for this has been one developer for a year. That's not much for a speculative shot at increased server efficiencies that could save them big money in the server farm. Once they've developed it, even if it didn't produce the gains they needed then releasing it is sensible as it gains them some PR amongst the OS community and may get more fixes from that same community improving the result (lower costs) for FB.