Dave Carver has published a, yet inofficial, XML Development Tools Proposal for Eclipse. I think this is a great idea. Not only because it affects the XML Security Tools I'm working on. The Web Tools Platform is great, but personally I think its scope is too diversified. Developing Web and Java EE applications is different, and XML is not necessarily used for web development (only). Surely the XML Development Tools and the Web Tools Platform would work closely together (as do most (if not all) Eclipse projects). But two projects make it easier for new users to find and install only the plug-ins they need to get their job done.
From all I have heard the last days (there was an interesting discussion on the WTP Incubator Dev mailing list) this new project would take a while, but it definitively is worth the wait! In the meantime have a look at Daves blog post on the topic or at the proposal mentioned above.