The OS X Lion v10.7.4 Update includes fixes that:
Resolve an issue in which the "Reopen windows when logging back in" setting is always enabled.
Improve compatibility with certain British third-party USB keyboards.
Addresses permission issues that may be caused if you use the Get Info inspector function "Apply to enclosed items..." on your home directory. For more information, see this article.
Improve Internet sharing of PPPoE connections.
Improve using a proxy auto-configuration (PAC) file.
Address an issue that may prevent files from being saved to an SMB server.
Improve printing to an SMB print queue.
Improve performance when connecting to a WebDAV server.
Enable automatic login for NIS accounts.
Include RAW image compatibility for additional digital cameras.
Improve the reliability of binding and logging into Active Directory accounts.
The OS X Lion v10.7.4 Update includes Safari 5.1.6, which contains stability improvements.
For information about the security content of this update, please visit: http://support.apple.com/kb/HT1222.