This Beta version is it seems to me unusually "uncooked" to me. Even though Lightroom product managers say not, I think Adobe rushed out this Beta to reveal the cool things they have in the pipeline and counter Apple's recent release of Aperture.
Michael Clark over at Inside Lightroom has a good summary of the new features. Undoubtedly the most significant feature is the ability to locally dodge, burn, clarify or sharpen in a non-destructive way. That is, in keeping with the fundamental Lightroom philosophy the original RAW file is not altered.