Can someone explain what this is? At first glance it appears to be Escape with prman capabilities. Could anyone tell me how much a license will cost, I'm very interested, yet can't find any info anywhere.

Try here:
http://www.sidefx.com/news/hescape/index.html [sidefx.com]

Edward: Thankyou for you reply. That was the first place I looked, of course. I know what Escape does but there is no mention of renderplus on this site. Any others?

That was the first time I've read that page and I was interested by the mention of RScript for render farms, what's that? Or is that Renderplus?
:?

Renderplus is the Third party rendering support option for Escape. This lets Escape users access other renderers such as Renderman and Mental Ray in the same way Master already does. The Renderman VOP tools are also available in Escape with RenderPlus. The prices is mentioned in the article link posted above.

Rscript is a version of Hscript that provides a non-graphical interface for generating ifds or rib files.

I might elaborate on that.

rscript is a cheaper, simpler version of hscript. The intention is that you use it to simply take a hip file and generate ifds/ribs. It doesn't allow you to do the hscripting tricks of changing object display flags, etc. It also doesn't allow geometry output, COP network output, etc. And you can't do the pre- and post- render scripts. But it does respond to the takeset command.

The way I think of it is: if you are using ‘takes’ to set up your render layers, then rscript will suit you fine. But if you are using the ‘standard’ Houdini technique of running hscript commands to create each output layer, then, clearly, you want hscript.