If you're in the WP community, then you've heard of the folks at WebDev Studios. Now, you have one more reason to love them. Check out the Widget Area UI Redesign they're working on for WordPress. Go check out the full article over on the company's blog.
I remember when P2 came out as the internal blog theme that the WordPress.com team used. Now we have a nice WordPress talk the UX of the theme from Michele Mizejewski. http://s0.videopress.com/player.swf?v=1.03
A lot of people have tackled drag and drop themes, but MiniMax is the first plugin I've really noticed that gives you drag and drop layout options within the actual WYSIWYG edit field for a post or page. Check out this overview: