Apple has released two new OS X Java updates, one for Lion, (Java for OS X 2012-005), and one for Snow Leopard, (Java for Mac OS X 10.6 Update 10.) The patches will prevent Java from running in an “always-on” state.
The java plug-in will be killed if no applets are run for an “extended period of time.” If Java for OS X 2012-004 wasn’t previously installed, 005 will disable Java by default until a person chooses to enable or re-enable a Java plugin in their browser.
More details available at http://support.apple.com/kb/HT5367 and http://support.apple.com/kb/HT1222.