Same idea as before really:
click the "people" link in the nav (it's the new members area) it sorts by last online...and like Miguel said, if it says less than a minute, they're online, sometimes even if it says 1-5 min ago :)
When you go to their profile and click ''more'' it should say when they last have been on. If it says ''last here: less than a minute ago'' then they're online.
go to there profile and look :)