http://home.comcast.net/~sdwoodgate/BizTalkServer2004AdvancedMessageBoxQueries.doc?
Take a look, read it over, use it when appropriate, send feedback. It has a lot of useful information on how to gather information programmatically from the msgbox. Hopefully all of this type of information will be exposed as perf counters, or through a BTS UI or some apis in the next release, but for now, here you go. I believe Paul Somers has also spent some time and might be making available a tool which will convert these queries into perf counters which you can adminster and monitor. I hope this helps a lot of you out.
ThanksLee