Something is keeping your wifi connection active/"in use", what are your powersaving settings? What connections do you keep open? Logoff your IMs and run powertop again (start it lock screen and kbd and wait 45seconds), if there is no change uninstall apps using the network connection one by one and run powertop in between so you get to know if it changed anything. Is foreca updating on view or timed? Is any other widget updating anything on the net? Is a ssh session open?

EDIT: could be a router setting you changed, what does it do with wifi offline?