Well R&R 2 was being sold at gencon. So I guess it is safe to talk now.
I don't have a copy on hand so it is remotely possible that this information is wrong since I am going purely off of memory. Please don't hold me to this.
The book is divided into several section, including the following.
It will have a section on the Astrology of Scarn. Covering the various constellations and cosmology of the world. There is also a large section on alchemy with many fun new things to create.
There are many fun new prestige classes inside, including a swamp necromancer and class that can call spirits into themselves. The second prestige class chooses from a number of animal templates that it may apply to itself.
I don't remeber much of the spells section except for a really cool coreanic spell that summoned a hammer and anvil to smash the casters enemies.
There is also a decent sized section of feats, including several very interesting ones for sorcerors. I also believe that there is an entire chapter on Psionics in the scarred lands.
Please keep in mind tha my memory could have failed me on some of this.