The current code base (as of apprx. 12/1/2002) has been tagged as beta1 and should be stable and releasable.
For beta2, I've put in these three major pieces:
1) an appender type architecture for logging. To extend logging, you just need to create an object the implements the P6Logger interface.
2) stronger use of the factories to reduce the amount of code necessary to add a module. Now, you just create a factory that extends P6CoreFactory and implement the (few) classes you need for your particular application. See the sample directory.
3) jdk 1.4 support. This was a submitted patch; I'll tell you who submitted it whenever Jeff gets around to answering his email.