I saw this white paper about 6 months ago in the Journal of the Computer Measurement Group (CMG). Two interesting points. First, they are using JBoss 3.2.3, which is missing several performance enhancements that make JBoss run well with SPECjAppServer. Those enhancements did not get in until 3.2.6, and again in 4.0.2 and later. Second, they are using SPECjAppServer 2004, which has a vastly different performance profile from the 2002 version. For example, in 2004 the database is much larger, and the network traffic is extremely higher. One anecdote: our network routers, who never minded the network traffic for high injection rates on 2002, shut down the network segments because of an assumed denial-of-service attack with a low injection rate on 2004.
Anyway, I presented a paper at last years JBossWorld conference on the work Unisys had done with JBoss performance and how we, along with the JBoss team, got it to scale very well on SPECjAppServer 2002. Not sure if that paper is still on line (it was earlier, but with the web site being updated for this year's JBossWorld conference, I couldn't find any info from last year's) You can see some of our performance tuning tips in the wiki at http://wiki.jboss.org/wiki/Wiki.jsp?page=SPECjAppServer2002Tuning