BEPUphysics

Is there any simple way to turn on anisotropic filtering? ...because the terrain look like a crap without it. Otherway i have to draw the terrain differently than simply passing it to entityDrawer as a DisplayObject.

The drawing system in the demos is meant as a visualization of the physics, and not so much a usable graphics engine. I'd highly recommend setting up your own rendering system if you're looking to make things pretty.

That said, the Terrain in v0.12.0's demos and earlier versions is just drawn by a BasicEffect. To turn on anisotropy, you have to set the appropriate sampler states.

Here are two relavant threads:
http://forums.xna.com/forums/p/12956/77312.aspx
http://forums.xna.com/forums/p/17846/94030.aspx