An early build of Windows 7 SP1 has leaked to file sharing sites this week, indicating that Microsoft is on target to ship the update later this year.
The build, 6.1.7601.16537.amd64fre.win7.100327-0053, appears to be a recent compile from March 27. Early reports, from enthusiast site GeekSmack, indicate the build is quick to install but it's not clear whether it includes the promised USB 3.0 support or enhanced Bluetooth and Wi-fi stacks.