There's some cool stuff in here, like using PackageKit for automatic printer driver installation as soon as you plug in your printer. The Anaconda installer has also been streamlined to improve the installation experience, especially in the storage devices and partitioning aspect.
NetworkManager has been improved considerably as well. "In Fedora 13 NetworkManager adds mobile broadband enhancements to show signal strength; support for old-style dial-up networking (DUN) over Bluetooth; and command line support in addition to the improved graphical user interface," the team writes.
There's a lot more in there for users, though, such as DisplayPort support for not only Intel video chips, but also Ati and NVIDIA now. The open source Radeon and NVIDIA drivers have been improved too; the 3D support for the Radeon driver has been moved out of the experimental phase, while 3D support in the Nouveau drivers has been added as experimental.