We have begun updating wiki.treyarch.com with details on the Mod Tools BETA, which will be releasing Tuesday, May 31st on Steam.
I wanted to highlight here some of the things included in the package: Launcher. Asset Manager. EffectsEd. AssetViewer. Maya 2009 Exporter Plugins. Reference materials: Maya src files, scripts, example mods, xmodel exports, texture assets.
The PC team is still investigating the potential release of Radiant. I'll be sure to update you when I know more.