R2 is a server technnology. It is essentially a specialized Windows OS for server management in file serving, printing and directory utilization workloads.
I hope that IT administrators will love it. R2 was designed top-down starting from practical scenarios for server management in small and medium-sized enterprise configurations. An example is when you have a large corporation with a lot of branch offices - you need smooth file and directory replication between all these computers. Another big theme in R2 is simplified storage management (and Iain mentions FSRM - one of the services that I am working on!).
You always learn one more thing while watching Iain - I liked his concept of how a server should be (quoting from memory): "When you install Windows Server, you should get basically nothing. Then, if you need directory services, you add AD. If you need printing support, you just add it."
Here is the Channel9 link.