Hi I have some more news for you. What was previously known as HIS (or now BizTalk Adapters for Host Systems) the beta program is available for anyone who may be interested. The program can be accessed on http://connect.microsoft.com. You will need an account with a passport to access the beta.
The April CTP which is planned for release on 14 April should include the BizTalk Adapter for DB2.
For information relating to BizTalk please start at 'Getting BizTalk Server 2006 Assistance'. This has links to most of the resources available for BizTalk.