iTunes wi-fi sync not working
I checked the Apple forums and several people say they fixed it by plugging iPhone into MB, it asked if to trust the device on the MB and the iPhone.  When trust on both is selected, it synced on the cable and now wifi sync is back to normal. May be this workaround will do the thing?

Also do you think Firewall can be an issue? 

Or Apple Mobile Device Helper process could be the bump, you can just force quit that process through Activity monitor