yes Grant has done screenplays! the Wikipedia article on him talks about it. that's wikipedia.org.

Lawn Mower Man.

:)

I know that he has written the screenplay for Sleepless Knights (not sure what it is about, but being Grant I'm sure it is mindblowing), and talked about We3 being optioned, but not sure if he is writing the script himself or someone else is. The Wikipedia article made me think that he is....

I think that when he is done with Final Crisis for DC, he may work on other things than comics. I hope he does some screenplays or novels. Between him & Neil & Warren Ellis, I would be a very happy man. Oh, and Mike Carey has a novel out as well. Warren's comes out soon.