Java 7 no squeeze do Debian

Question

Eu tenho o Debian GNU / Linux 6.0, o apt está configurado:

# squeeze
deb     http://ftp.cz.debian.org/debian/     squeeze main contrib non-free
deb-src http://ftp.cz.debian.org/debian/     squeeze main contrib non-free

Eu quero instalar o Java 7, mas o apt não o vê:

apt-cache search openjdk
openjdk-6-dbg - Java runtime based on OpenJDK (debugging symbols)
openjdk-6-jdk - OpenJDK Development Kit (JDK)
openjdk-6-jre - OpenJDK Java runtime, using Hotspot JIT

O que está errado?