Which version of Sun Java have I got?

[Colin Law]

In another thread it was pointed out that we should be using Sun Java
6.24 rather than 20 as this had security issues.  When I type
java -version
I get
java version "1.6.0_20"
OpenJDK Runtime Environment (IcedTea6 1.9.7) (6b20-1.9.7-0ubuntu1)
OpenJDK Client VM (build 19.0-b09, mixed mode, sharing)

But when I do
sudo apt-cache policy sun-java6-jre (or bin or jdk or whatever)
I get
sun-java6-jre:
  Installed: 6.24-1build0.10.10.1
  Candidate: 6.24-1build0.10.10.1
  Version table:
 *** 6.24-1build0.10.10.1 0
        500 http://archive.canonical.com/ubuntu/ maverick/partner i386 Packages
        100 /var/lib/dpkg/status

I am not aware of having installed it other than from the repository.
Can anyone help with my confusion?

Colin