(Update: See the latest on the Deployment Framework here.)

Addressing a few comments/questions that have appeared -

1. Bootstrapping your binding file: It was pointed out that a bootstrapping process is required for your initial BizTalk Orchestration binding file.  This is quite true - you either need to manually deploy your orchestration(s) and associated assemblies, and use the BizTalk Deployment Wizard to create a binding file, or you need to create a binding file by hand (using a previous file as an example...)
2. Automatic maintenance of your binding file: Hermo Terblanche would like the binding file to be maintained automatically (as part of the build process.)  One could imagine automatically “refreshing” this file using BTSDeploy at build time.  However, there is a question of what the source of truth should be for your bindings - I would argue it should be the binding file, not the current configuration of the server.  Others might disagree, at least during development.
3. Rule deployment: Chris Delaney is looking for a method of deploying rules.  There doesn't appear to be a command line tool for this (that you could call from NAnt), but it looks somewhat trivial to write.  See \program files\microsoft biztalk server 2004\sdk\samples\business rules\business rules hello world2\HelloWorld2.cs - specifically the LoadFromFile and DeployRuleSet methods.