We did ship with JBoss Serialization at one point, but turned this off after a while, prompted by some reports that JBoss Serialization was hurting overall performance (and adding an extra jar to the distro).
An explanation from an email conversation I had with Clebert Suconic, the JBoss Serialization maintainer:
"Clebert Suconic" wrote:
in recent Java5 (they have ported the fix to java4 as well) they have
fixed the synchronized caching what was one of the advantages of jbser.
(don't know if pressured by jboss-serialization or not).
So basically the main benefit of JBoss Serialization is now in more recent patch releases of Sun's JDK. In the end though, I'm sure there are some use cases (depending on the number and type of objects being serialized) where JBoss Serialization may perform better.