You can use it in temperate, tropic and arctic climates and, using a parameter, choose which track type to replace. There's also a new depot to distinguish it a bit from normal rails.
There are no finished narrow gauge trains sets (yet), although I think Wile E. Coyote's Serbian one is pretty close, and the UK one is sort of getting there.
If you find any problems or have any suggestions please let me know. Oh yeah and if someone could test the DOS version that would be handy

EDIT: 10/09/2005 - v0.91 Arctic snow rails corrected
Newest Version - v0.93 - Info and links to download Here