i promoted our jboss cluster to production on thursday. our site gets about 50,000 visits per day... not hits, visits.
in production, jboss replaced 5 websphere 5.1 machines and apache over 2 ibmihs boxes.
include qa, development and staging environments migrated and the count goes to 25 jboss instances that replaced websphere. apache another half dozen or so over ibmihs.
administration of the clusters is much simpler than it was for websphere. nodeagents, deployment manager, fix pack wizards, all that crazy crap is gone.. now, simple clean perl scripts do most of the magic.. even staging deployments of new code release by our developers.. auto magically..
cost of administration in terms of administrators time has decreased significantly. and well, if youve ever been billed by IBM you can imagine the savings there ;) ...