I have been using SonicMQ for about 5 years. Rock solid - just works. And when it doesn't, their support people are very helpful - they dig into your problem and crush it. If the problem is a defect - they fix it. If the support person can't figure it out, they work with engineering. If they still can't figure it out, they get engineering on the phone. And they keep following up with you. Really can't say enough about the success I have had with the product.
Anyway, there are some improvements that will help me that I am looking forward to. We use pub/sub, durable subscriptions, and Sonic's "shared subscription" feature extensively. They apparently have some fixes/enhancements that will prevent messages from getting trapped on brokers when bad things happen. I have had this happen when consumers of a Topic on a node in a cluster get horked.
They also are introducing (don't know exact name) "MultiPublishers" and "MultiSubscribers". Apparently, this feature was driven by wall street customers who have thousands of Topics. It takes 100ms to register a subscription at start up. This adds up when you have thousands of topics in use. So, my understanding is that with "MultiSubscribers" and "MultiPublishers" you can add Topics to a Set and register them all at once.
They also apparently tricked out the "Continuous Availability Architecture" (CAA) further. This is wicked cool and I don't know anyone else who does it. Basically, you can have a client publishing to BrokerA, kill -9 BrokerA, and the client just fails over to "BrokerB" and continues publishing ... even within a transaction. And this takes 10 minutes to set up. You don't need exact hardware, bios settings, etc. (i.e., hardware based failover). You just configure your setup that way. Another thing that is huge when fault tolerance really matters (more and more these days). You can recover within 10 seconds vs. 10 minutes. Wicked cool.
Anyway, I'm not the type to spaz out about a product like this - I am a huge skeptic from years of being let down by integration companies. Sonic just makes things stupid simple like they should be - so you can get on with SOA & EDA.
Update 17-JUL-06 - Now that it is possible to determine my employer by reviewing my blog posts, I must follow my employer's blog policy.
This is not an endorsement by Liberty Mutual, but my personal view. Vendors are NOT free to quote with attribution.