These are amazing deals. They really want to launch the 2014 model well so they are really giving away the 18 month lease to get you back in the dealer when they show up.
The best deals I've seen, people are getting payments in the mid to high 200's for loaded G37 sedans. Most dealers are at least doing $5k off MSRP on any model, and if you're a current lease customer there's an extra $1000 loyalty bonus.
FYI- you may want to look into the buy special as well. Infiniti is giving dealers an extra $3k on purchased cars (financed or cash) so you can get a 6MT Sport model for about $34k ($42k msrp)