Saw on Frontier's Wikipedia page that they had several A320's on order, but hadn't heard anything more about it. One of my FA's last night provided some more details. She said that Frontier is going to take delivery of them starting in February, and that they are going to be put in service on the DEN-DCA route, which apparently has lots of demmand but is limited in expansion due to the small number of slots available at DCA.

Also worth noting, she believed that they would have two exit rows with 2 emergency doors on both sides, in a (2-3) configuration, so someone's going to end up with "infinite" legroom on each side. Looking forward to a ride on their new craft, and I'm glad to see Frontier continuing to do well and expand!