The BizTalkDisassembler NET Reflector add-in will allow you to list all BizTalk artifacts contained in an assembly and extract them.

Installation:
Donwload files and extract Reflector.BizTalkDisassembler.dll into the same directory as Reflector.exe. Go to View | Add-Ins in Reflector, and Add Reflector.BizTalkDisassembler.dll.

Usage:
- Right click on the BizTalk assembly and select "BizTalk Server 2006 Artifacts".
- You should see a list of all artifacts, with their type, name and namespace they were compiled into. Click the "Disassemble..." button to disassemble all selected artifacts into files. You can select / de-select artifacts by using the selection check box on the right.
- In the disassemble dialog, specify the path to the directory where files should be created and press "Disassemble". The disassemble dialog is multi-threaded for a more responsive user interface.