http://thepcenthusiast.com/5th-gen-intel-broadwell-processors-release-date/It's a tough one. I'm really waiting on a new iMac, and i want 4K support so i can't buy the current one no matter how good it currently is. The fact that a new iMac was referenced in the 10.9.4 beta suggests it must be coming soon because if they were going to wait for Yosemite to come out they wouldn't bother updating Mavericks to support any new iMacs. So it has to be before September surely.
;-)