Yesterday Microsoft released a BizTalk 2004 Adapter for MSMQ v2.0. This works with MSMQ 2.0 and 3.0.

Here are the key features from the download site:

The BizTalk 2004 Adapter for MSMQ provides support for sending and receiving messages using MSMQ 2.0 and 3.0, and takes advantage of the new features in MSMQ 3.0. Major features of the adapter include support for:

• MSMQ 2.0 and 3.0
• Multi-threading option for faster performance
• Guaranteed delivery when using transactional queues
• Reading from remote non-transactional queues
• Dynamic send ports
• Support for messages up to 2 Gigabytes in size

Download this adapter here.