I had lunch with Gavin King (original author of Seam) last week, and we had a very interesting conversation about the work I've been doing with the Ajax4JSF team's excellent GWTJSF integration library. (See http://unrealities.com/seamgwt for that.)
We wound up discussing what it would take to make it easier to write JSF components with GWT. I wrote a blog post about it here:
Anyone interested, please speak up here, or in the comments thread in that post.
Very interesting. Have seen the history management of GWT. Get together a4j/richfaces, gwt and seam. It's great.