Here are a few useful links to information about versioning in BizTalk projects and web services
I would probably start with the web cast as it is a good introduction to the topic by some guys from the BizTalk Rangers team at Microsoft.
I have noticed a few sites that seem to copy the content of blog articles and display them in their own site. It is a bit annoying that they do not clearly reference or acknowledge the author so I have decided to put this note on the bottom of all of my posts from now so it is clear who wrote it.
This article was written by: Michael Stephenson
The source of this article is: http://www.geekswithblogs.net/michaelstephenson