MOM - Message Oriented Middleware for Rails

I would like to develop a monitoring system with Ruby and Rails. I
will have the agents in the server and the monitoring system, with a
poller that will notify the Rails application.

I have tested ActiveMQ, with JRuby and Ruby and works fine. I will
test the ActiveMessage plugin for an Rails easy integration. I
wondering what are the more popular and reliable choices on Rails for
MOM. I saw that someone uses XMPP, some AMPQ implementation
(RabbitMQ). Any advice?

P.S.: I need to send text messages but I need to send serialized
objects too (data objects containing CPU, disk... info).

Thanks,

Riccardo.