Well, it's not exactly new considering it was really released back in January, but considering it's been around for eons, it's still pretty new. Just visit the official site and download it now if you want to make some terrains, but beware that it takes a little more than a few click if you actually want something really nice.

http://www.planetside.co.uk

Oh, and here's a little something I just put together with it in a few minutes:

"Stephen Wolfram is the creator of Mathematica and is widely regarded as the most important innovator in scientific and technical computing today." - Stephen Wolfram