I must be old school, but I remember when Vegas was cheap in the summer because it was simply too hot to visit and the rates were dropped to entice people to come. Now, places like Red Rock (!) are charging $699+ for a room.. yikes.
The rationale is..? (And i thought the economy wasn't doing to well)
Disclaimer: It's pretty obvious I haven't visited Vegas in the summer in a *VERY* long time.