What is MSMQT?

Interesting little overview on why there's an MSMQT at all -
What is MSMQT?:

MSMQT ships with BizTalk 2004 primarily to get around the 4MB MSMQ limit which was a pain in previous versions of BTS and any other application that used MSMQ, this means you can now chuck big messages at BTS via MSMQ with ease, and BTS implements streaming of messages so it doesn't have to load it up in memory to do any processing (unless you want it to).

Another good reason to make sure your pipeline components properly support message streaming!