Java doesn't work in mozilla 0.7.
I've done some investigation and this looks like it's a glibc issue. You can use bits of the standalone java VM that mozilla uses and those standalone parts don't work on the 7.1 beta. You can get a copy of the standard jdk code at: http://people.redhat.com/blizzard/java2.tar.bz2 If you untar it you should be able to cd into the bin/ directory and run ./java -version and it should print out a version string. It works on 7.0, anyway.
This is a buggy JDK (it has hardcoded knowledge about thread stacks being 2MB in size aligned to that size). We're now discussing what do with that. Particularly at least os::Linux::install_alternate_signal_stack(void) contains this bug.
Opening up so that the sun people can look at this bug.
Should be fixed in glibc-2.2.2-7 and Sun is actually working on a fix using pthread_getattr_np.