Eidos has announced the release of the Deus Ex software development kit (SDK), a toolset that will let users edit and create missions for the first-person role-playing game developed by Ion Storm. The SDK features the tools necessary to create new stand-alone missions, build 3D maps, or modify existing maps. These tools include a Deus Ex-ready version of the 3D map editor UnrealEd, a conversation editor, and a tool to convert 3D objects created in Lightwave to the format used in Deus Ex.
If you're interested in trying your hand at Deus Ex editing, then grab the 5.1MB SDK here. It's likely that fan sites such as Deus-Ex.org will soon have new user-submitted content created with these tools.