I found out the hardway that the jre included in the spark download will not work with fedora 8.
Since fedora 8 comes with their own jre now, just make sure you have them installed.
This is what I have.
rpm -qa|grep icedtea
Once you have downloaded and extracted the spark tar.gz file, go into the Spark directory and add the following line at the top after #!/bin/sh:
You should now be able to launch spark.