I'm not sure if any of these people have contacted you already (I have suggested they do so), but you might find these couple of websites / blogs interesting -

Darren Neimke's blog - http://markitup.com
this describes both SingleUserBlog (SUB), and BlogML. Note that the blogging software for that weblog is SUB.

BlogML Project on GotDotNet - http://codegallery.gotdotnet.com/BlogML

What is BlogML?

The category on Darren's blog devoted to BlogML is at - http://markitup.com/Posts/PostsByCategory.aspx?categoryId=5751cee9-5b20-4db1-93bd-7e7c66208236

Here's a starting point, in Darren Neimke's words -

"Have you ever had a blog and wanted to move to another one?  Maybe you had an early version of .Text and wanted to move to an upgrade or to CommunityServer when it came out.  Maybe you had SingleUserBlog and wanted to move to DasBlog.  Did you end up doing it or was it just too difficult?  Read on to hear me explain about how this will be a no-brainer in the future..."

Implementations of BlogML

So far, there are implementations of BlogML by Jim Vrckovski who recently installed SingleUserBlog and, to migrate out of his existing .Text blog, wrote a .Text implementation of BlogML - http://codeinzen.net/Posts/Post.aspx?postId=c0685180-143b-423f-9bb2-1a3600dcf296

and by Grant Holliday (a guy that Darren works with), exporting Blogger blogs to BlogML format -   http://dotholliday.blogspot.com/2005/09/export-blogml-from-blogger-to.html

Also, check out this blog post by Darren - Is BlogML better than the MoveableType import/export feature?

Last couple of links: SingleUserBlog is referenced here - http://markitup.com/Posts/PostsByCategory.aspx?categoryId=bc1e0ae5-7908-452d-a936-f296ba379f23

and the sourcecode is available here - http://projectdistributor.net/Releases/Release.aspx?releaseId=220

Cheers - Ian Thomas