Just noted that you can´t sign Android APKs with the Java 1.7 jarsigner. So I wonder why this is and what is the difference between the 1.6 and 1.7 signer?
This is because the default digest algorithm for Java 1.7 is SHA-256 while for Java 1.6 it's SHA1withDSA.
Java 1.6 Jarsigner docs
Java 1.7 Jarsigner docs