Ubuntu has sent out an announcement that it will be pushing a security update that disables the Sun JDK browser plugin on all machines. It seems that there are several security issues with this plugin, but, due to a change in licensing by Oracle, it is no longer possible to create packages with the fixes. The best solution appears to be to switch to OpenJDK.
December 16, 2011
Ubuntu Disabling the Sun Java JDK Browser Plugin
Read more at LWN