If you read the post where Andy talks about releasing the Automattic stats plugin for self-hosted WordPress, he mentions a few things that make it interesting - notably that the system "only supports WordPress". Then he also mentions that anyone with a thorough understanding of WordPress and XMLRPC could clone the plugin to make it work with other platforms.
I don't claim to have such knowledge (of either WordPress or XMLRPC), but I think I've managed to do just that. Make it work with another platform, I mean. Some time ago, I managed to get the blog registration piece working, which really wasn't that hard - you simply pass some data to the system along with your API key and in return you get your blog registered. Not too bad. Then I ran into a speed bump of rather monumental proportions. Actually it wasn't that the bump was particularly large, it's that I hit it and then had about a million other things to do. So I put everything on the back burner.