Shane "Fishman" Sherman sends word that WorldCraft 2.1 is out, and available for download over at GameDesign.net. You'll note that this version is only for Half-Life. Here's a list of changes in the new version:

• Fixed crash when selecting large entities (the TFC entities for example) after placing them in the map.
• Moved registry keys to be independent of Worldcraft 1.6, so now 2.1 can coexist with 1.6.
• Added a new mouselook navigation system. Press 'z' to toggle it on/off. ASDW keys work like in Half-Life. This system can be disabled from the 3D options page and everything should work the old way.
• Streamlined memory allocation to be more economical.
• Fixed a crash when an entity in the game data file had a type "flags" or "choices" variable and another variable of the same name but with a different type. The only way to test this would be to add this error to the FGD file.
• Added an autoupdate utility so that Worldcraft can be updated over the internet.
• The old lights.rad has been renamed valve.rad. The new lights.rad contains only one entry (for +0~WHITE). If you want the old lights.rad file, copy valve.rad over light.rad.

He also points out a few caveats: this is a full install (so it's a beefy 8 meg download) and it'll overwrite your CmdSeq.wc, so back that up if you're installing on top of an older version (if you make Half-Life levels, that makes sense, i'm sure).