What about Alex Garland, who was reportedly paid $1 million for his screenplay? It is not rare for a studio to bring in another author to clean up and tweak a script, and that's our guess for what Weiss is currently doing. Weiss is also working on "an entirely new second draft" for the Lucky Wander Boy adaptation as well as tackling Ender's Game alongside David Benioff.
If nothing else (director, actors, production dates), at least the script is working out.
[update 1: In an e-mail exchange, Weiss told Joystiq that, while he can't say much, he is "doing a rewrite on the Garland script for Halo." Also, since a Joystiq commentor was curious about Ender's Game, Weiss said this: "Orson Scott Card wrote an Ender's Game script, as did Michael Dougherty and Dan Harris, and myself."]