Update from Higby via twitter:
mhigby Matthew Higby
@mstorer3772 We haven't locked that down 100% yet, it's a bit too fast internally. I have a feeling it'll be a couple hours long eventually.
2 hours? Maybe. That sounds good to me.
EDIT:
Yet another answer, this time from SOE_Hack (producer of PS2):
@SOE_Hack Josh
@mstorer3772 @planetside2 something we've been playing with, but we'll really need to balance the day/night cycle during beta.
You'd think they didn't talk to each other or something.