GtkRadiant under GPL
gnarlin writes "GtkRadiant is now available under GPL license, along with some Quake II tools which never got a chance to be put under GPL before. Head over to the qeradiant website for all the details. GtkRadiant is a level editor developed by id Software and Loki Software. It is used to create maps for a number of computer games."
Radiant is already a very good tool to work with. The version that I used back when I was using it to make a mod for Call of Duty it did have serious crashing errors, though. I hope that fixing these bugs will be the first priority of whoever's interested in working on it.
Found a bug in GtkRadiant ? Submit a bug report at http://zerowing.idsoftware.com/bugzilla/