Shawn Wildermuth demonstrates through a short video the most important according to him update in WP7 NoDo - the copy and paste on the phone.
Source: Shawn Wildermuth's Blog
I was playing with my newly updated Windows Phone 7 (with the March 2011 - or so called NoDo update). While I can attest I can sense the speed increase, especially in games and in tombstoning of applications; the big feature is copy and paste on the phone.
I recorded this short video to show how to use Copy/Paste (as well as how to repeat the operation: