You can read the announcement here http://blogs.jetbrains.com/idea/2009/05/maia-eap-is-finally-here/
I've already given it a try and although there's a critical bug (it still tries to find tapestry classes under the old package org.apache.tapestry) things are looking good. Because i was involved in the conception and initial implementation of this plugin i know that if they get everything in place and working it's going to rock. It will provide lot's of cool feature like embedded documentation, support fot drag&drop, lot's of wizards, syntax highlighting and auto-completion on templates and lot's more. Hope it's more stable on feature releases thought. Cheers, Hugo
