The long-awaited first update to OS X Lion, version 10.7.1, has just hit Software Update.
The update is relatively small, weighing in at 17.4 MB for an iMac, and requires a reboot after installation. Apple recommends backing up your Mac prior to updating.
The update:
Addresses an issue that may cause the system to become unresponsive when playing a video in Safari.
Resolves an issue that may cause system audio to stop working when using HDMI or optical audio out
Improves the reliability of Wi-Fi connections
Resolves an issue that prevents transfer of your data, settings, and compatible applications to a new Mac running OS X Lion.
Additional notes can be found here: