GeekSmack has released screenshots and information on the upcoming Service Pack 1 for Windows 7. While this is a leaked version, it is a recent build, from March 27th. Fast install, hopefully a few fixes not available yet. SP1 is also supposed to support USB3, and a better Bluetooth and WLAN stack. No word on those, though.
The install process is much of what you would expect from a service pack installer, but one thing I noticed is the installation is MUCH faster than the install process for service packs on Vista was, which is a very welcome change.