Kegetys has released the 1st modded track for Assetto. It is a rally stage ported from Richard Burns Rally, 70 mb.
Supposedly it's very good, I have yet to try it though.
Here is the discussion link:
http://www.assettocorsa.net/forum/index.php?threads/joux-plane-track.4529/
Rally? you didn't say it has rally stages, are there proper rally tyres available?
Don't get too excited, I think it's a tarmac stage :) . There is nothing to do with rallying in Assetto yet (tyres etc). I'll let you know more when I get to have a go.
I have had a go and it's very good. It's a bit buggy if you come off the road...but your not supposed to do that anyway :). It's a full tarmac stage.
The developers don't like this track being discussed / shared on their site so you may find it hard to get now.
Here is the direct link for anyone who wants it:
http://junk.kegetys.fi/ac_joux_plane12.zip 70mb
This track became Bugged in a update about a month ago. Kegetys, the creator, has released a fixed version:
http://junk.kegetys.fi/ac_joux_plane13.zip