I just picked up my 07 and I have the same Key Fob that shows in the very first post of this thread - as well as a seprate Infiniti key for the Ignition which contains a programable micro chip that communicates with the ECU. - that looks and is cut like your ordinary key.
Looking at the brochure - the Automatic Tranny G35 Coupes are equipped with Infiniti Intelligent Key - which will communicate with the car without the key ever leaving your pocket (or purse for the ladies and mistresses).
Therefore - the 6M models will have the old Key and Key Fob combo while the auto's will have the Intelligent key.
Infiniti Canada - 2007 Infiniti G35 Coupe - Technology
If you even take a look at the interior picture of the web page - it shows a slot where our normal keys would be inserted - and for further details - Infiniti Intelligent Key is outlined above.