A few days ago we turned on the new 6.0 Web Mail interface for a limited number of users, and we'll be increasing that after Christmas so look for it. You can see a picture of what to expect earlier in the blog (scroll down the main page). If you are already seeing the new interface, please send feedback using the Feedback link that is in Web Mail (at the upper right in the new layout).
I will be unavailable to respond to or publish blog comments after today until January 5, so I'll be disabling new comments until then.
I'll catch up the currently pending ones today.