Fiorano has a bridge product for MSMQ and MQSeries.
The datasheet, docs, & download links are off of http://www.fiorano.com/products/products.htm
From the datasheet:
Together, the FioranoMQ Server and the FioranoMQ Bridge enable you to send all types of JMS messages including Srings, Bytes, and Streams, etc. to an external messaging server. In addition, you can receive messages from either a MSMQ or IBM MQSeries Server. Messages are converted to a appropriate JMS message format and is transparent to the FioranoMQ user.