I'd like to start by making sure everyone knows that the Microsoft TechEd sessions are available online. There is some great content that is definitely worth checking out.
Today, I'd like to highlight the talk on the T-SQL OVER Clause presented by Adam Machanic. Sure, you can always go to the reference page on MSDN, but Adam manages to make this super-clear by starting from the GROUP BY clause and going from there.
If you do nothing else today, go download the PowerPoint file and read it in five minutes and your brain will grow immediately, then schedule some time to go see the whole thing online.