Yes, it has been covered on this forum, at least once. Certainly, it was mentioned in the “is it OK to use J2EE?” thread, but also in other ones. I believe (not entirely sure) that each thread that mentioned JMS also mentioned at least JBoss or J2EE at some point. Search with enough days (700?) and all categories (ISTR several started off not in networking) should get all of them.
Approximate conclusions IIRC were:
theoretically, it's great. For some particular uses, it's fine, but most of those are small games where the overhead of importing JMS's architecture is too much hassle to justify it.
In practice, you have to pay $$$ to get a halfway-decent JMS implementation. Apparently, most of them are crap (not surprising, given what it does and how much money messaging middleware vendors have charged and still do charge for good implementations of this stuff - Sun wasn't going to make an expensive product free overnight, now were they? :)).
…or something like that.
I’ve not really tried them myself - why bother trusting a random messaging layer when you can just go and get ones designed specifically for games? Like J2EE itself, the guarantees are few and far between, and it’s not really designed with games-like traffic patterns in mind.
FWIW, I’m planning on releasing an open-source networking layer sometime 2005Q3 as part of writing my networking book. It might just be a port of eNet or similar, or it might be something entirely new; I’m not sure yet.