JBoss is one among the top 3 application servers currently available. I personally know of applications which are currently in production on JBoss. As far as acceptance of JBoss in various countries is concerned, i dont think region is a factor in deciding which server is used for your application. Sometime back, a similar question was posted and Mark had a really good answer.
It's definitely number 3 behind Websphere and Weblogic. In the past, I generally see it in testing enviroments, but have been seeing it in production recently -- which I am guessing is due to the fact that it is now supported by RedHat.