the issue with java7/openjdk7 is that they have linking issues with their own libraries so adding them into LD_LIBRARY_PATH should get you out of safemode :)
here is an example command using firefox and openjdk7
32bit:
LD_LIBRARY_PATH=/usr/lib/jvm/java-7-openjdk-i386/jre/lib/i386 firefox
64bit:
LD_LIBRARY_PATH=/usr/lib/jvm/java-7-openjdk-amd64/jre/lib/amd64 firefox
It works for the unix client and once the public testing is done (to see if this causes any other issues) i will make an automated script to fix it :)