I'm a little confused as to how the new iMacs work as monitors for other devices. If I wanted to plug in two VGA only devices into the iMac I could use both Thunderbolt ports with a Thunderbolt/Mini Display to VGA adaptors right?
No.
As Thunderbolt has a bit of new wiring, new 27" iMacs only accept input signals from other Thunderbolt devices like the 2011 iMacs and 2011 MBPs.
Therefore you need a converter, to convert the analog signal properly, and they haven't been released yet.
Maybe using MRoogle will help you find similar threads, as it comes up every once in a while.