Both Unisys and HP at one time or another worked on benchmarking JBoss AS (though for earlier releases than 5.x). Each presented some of their observations and tuning hints at various JBoss World conferences. However, the SPEC license agreement specifically prohibits publishing any SPEC benchmark result without approval from SPEC, which means that any official benchamrk results would have to be found on the SPEC web site. Last time I looked on their web site there were no JBoss AS numbers posted.