I don't think that an iMac is ever really off, so it should be no different than WOL on a PC which works when they have a remote power switch (i.e. a switch on the MB not the Power Supply.
Any updates on this? Would really be nice to have this feature available since you never know which user perform a "Shut Down..." on their iMac end of day when they go home. Getting tired of running around all offices and turning them back on when we do maintenance and since this is working on the PC side I must say this one thing is really annoying with Macs... Was suggested to install "Hackintosh" systems by the CFO as she is counting every $$$ for longer overtime...