What happened was – I have moved to Java 5 since RC-2 release so I compiled the public build of RC-3 on it. The Java compiler (javac) has one thing – if you didn’t specify desired JVM version in its ‘target’ parameter, it supposed the compiled classes compatible only with the current version. I overlooked this fact at all and got Memoranda 1.0-RC3 release built as “JVM1.5-only” though the sourcecode was 1.4-compatible. I got it only when 1.4 users begun to complain. So, I was forced to rebuild it and release the 1.4-compatible update.
A good lesson for a release maintainer. “Build Once Run Everywhere” is not so simple, you see.