Yeah, somebody used HL2 textures in their doom 3 map to test how things will turn out. And from the screenies I seen, it is suprisingly good.
http://www.doom3world.org/phpbb2/viewtopic.php?p=64270&sid=3ff42dfddc0d2de21b0d04744eb4d465#64270
http://www.doom3world.org/phpbb2/viewtopic.php?p=64270&sid=3ff42dfddc0d2de21b0d04744eb4d465#64270
\(='_'=)/