First - thanks for the great work you do with MyFaces. It's an awesome product and it's wonderful to have an independent implementation of the JSF spec!
I am the author of Metawidget (http://metawidget.org), a JSF component that does a lot of runtime component tree manipulation. This was unreliable under JSF 1, but JSF 2 introduced SystemEvents which promise to make this more solid. I believe Metawidget exercises SystemEvents more than most, and as such I am seeing problems both in MyFaces (2.0.2) and in Mojarra (2.0.3).
As a bit of fun I have created a small Acid Test (inspired by http://acidtests.org) for SystemEvents. I would be most grateful if you could work through the 3 tests and get MyFaces working with them. Basically the tests all use a combination of PreRenderViewEvent and tree manipulation. Full instructions are included on each JSF page. Of course, there may be bugs in the test itself in which case feel free to point them out