Does somebody know how to mod UT3 or how to make new maps with the editor ?
I know that the special edition includes some tutorials, but is there any site for UT3 modding ?

i just searched google for a while, and all i found was a filefront mod site. Maybe make your own Maybe there wil be one when the game is released though. Or order the special edition so you get the 10+ hours of tutorials (i am)

I assume since it uses the Unreal Engine, it probably uses the Unreal Editor. Look in the game files for it.

EDIT: Woops, I thought you were looking for the editor.

Try looking at this tutorial. I know it's for Republic Commando, but RC uses the Unreal Editor too, so it should be similar.

Well. Unreal Engine 3 and Unreal Engine 2 - Down are totally different beasts. Pretty much same layout in the Editor, but from what I've heard... it's more complex and difficult than previous editors.