I am on linux and it does not seem that anytime in the future that hammer will be ported to linux. The map compiling toolset is already working on linux with some minor hookups in the vrad but the posix ports are getting pushed up stream some time so they will be fixed eventually. The only real major hookup I see is getting all the map data that hammer uses, like the types of items and entities from what it is named/called in DR. all .vmf is is a text file with a bunch of { } sections. is .map a binary format? and what ever anyone thinks they all have the same root family to quake map format in there some where. Unless valve drastically changed it, it should be close to the map format.