Intel was late with Ivy bridge and when they finally released Ivy they are already in spreading the rumor about Haswell...According to their road map for Haswell...Intel plan is Q1/2013 announcement and end of Q2/2013 release....This info I actually have in their road map and I would like to show you Intel confidential PPT but I cannot...maybe i take one or two slides to show...Launching a "new" iMac with a 6 month old processor is a joke. Full stop. It should have been released 6 months ago.
Originally Intel wanted to release Ivy for desktop much sooner but they was late...And longer time is passing Intel starting to make more and more launch delays..People from Intel who gave us presentation was even joking about delays that they have..This delay will hit Haswell as well....So to answer your question you will buy refreshed iMac or you will need to wait at list 9-10month before you get one with Haswell CPU in it.