It's not mentioned in the text of the post itself, but the $495 price represents a 75% discount on the previous price. A far more detailed overview is here for those interested: http://www.fxguide.com/featured/rendermanris-and-the-start-o...
It's possible they were hemorrhaging money thanks to the Arnold and VRay competition over the past few years.
Looks like ILM are being "coerced" into using PRMan again from what I hear...
But either way, it sounds like either they're willing to take a hit on the profits, or they're expecting to make up for it from renderfarm expansions...