Two main vulnerabilities covered in this release. Microsoft Windows Shell shortcut vulnerability (CVE-2010-2568) and the Siemens Simatic WinCC and PCS 7 SCADA vuln (CVE-2010-2772). Both of these are being actively used by the Stuxnet worm.

More details are available here: http://www.snort.org/vrt/advisories/2010/07/22/vrt-rules-2010-07-22.html