I'm sure lots of people are blogging a ton about PDC stuff, but I wanted to call out two things quickly.
First is Microsoft Max. I have a friend on this team, so I've heard a bunch about this. Given the number of pictures I have taken of my kids, I can't wait to play with this in earnest.
Second is LINQ or Language Integrated Query and it's use in C# 3.0 and VB 9.0. I started to write a language a few years ago called Dart (named after my dog) that had SQL-esque commands that were strongly typed. So I'm really impressed with what they've acomplished in LINQ. Not only is it doing strongly typed queries in the lanugage, they even can do joins across stores! In the keynote demo, they joined a query of running processes with data from a database. So now any C# or VB developer has their - or should I say will have their - own query processor around at the ready!