The latest version of Java gets its first significany update which mainly constitutes of security patches for across the range of Java products (JDK, Runtime Environment and so on). This critical patch corrects 20 security issues in total.
The vulnerabilities are to be found in update versions 27 and below, so if you are on one of these then you will need to get the update. If you're not sure then go to check, and for more indepth information check the risk matrix which outlines the affected components and attack vectors.
As well as the security fixes, some minor bugs have been squashed too such as Olson time zone data which is now updated to 2011g and Cisco AnyConnect Mobility Client and Microsoft UAG Clients were added to the Blacklist.
Release notes can be found here:
As always, downloads links can be found here: