I'm building Monday for the web and iPhones+Androids in full HTML5, with help from Backbone.js, Appcache and Sass+Compass, and it's an amazing platform! I can't wait to write more about the stack and the lessons I've learned building and debugging it all.
But anyway, I'd really love your feedback on the Monday front page and to hear your expectations from calendars. I've got some time left in the big vision hourglass until I head back to hacking.