I don’t know whether this officially documented anywhere but it looks like WebObjects is now free for development on Mac OS X.

I just installed WebObjects 5.3 with Xcode 2.1. At no point did the familiar " Enter your license string" dialog appear and when the install was completed, the file "/System/Library/Frameworks/JavaWebObjects.framework/Resources/License.key" contained a license that didn’t match my previous one.

The WebObjectsLicenseUpgrader.app shows this as being a full WebObjects Developer license.