Joep, I have a few questions on your plans for a 0.22 release of Hadoop. Are you planning on releasing a version of 0.8 Pig that works with 0.22? I would suggest working with 0.9 or trunk instead since a number of significant features that your users will find useful (macros, python embedding, works with HCatalog, etc.) have been added. You are of course free to pursue whichever branch you prefer.
Also, I'm curious how you plan to test this release. I think it would be really good if you could get the end-to-end tests running against this before releasing it to assure you have adequate test coverage.