Major Description
Looking at the current package for Spark - it packages a lot of things that are not necessary, and is missing some others that might be useful.
bagel/lib/spark-bagel_2.10-1.0.0-*.jar
core/lib/spark-core_2.10-1.0.0-*.jar
lib/*
mllib/lib/spark-mllib_2.10-1.0.0-*.jar
repl/lib/spark-repl_2.10-1.0.0-*.jar
streaming/lib/spark-streaming_2.10-1.0.0-*.jar
None of the above are necessary, since they are already packaged in assembly/lib/spark-assembly-1.0.0-*.jar, which is what everybody should be using.
examples/lib/spark-examples_2.10-1.0.0-*-javadoc.jar
examples/lib/spark-examples_2.10-1.0.0-*-sources.jar
Again not necessary, just because, well, anyone who needs that can use maven.