Tim Heuer built a simple manifest for the new beta of Windows Live Writer (which has a UK dictionary, worth it for that alone). With his permission I took his image, and put it into the trunk along with a manifest. From that I'll be building the parts of the Wordpress API that make sense for Subtext, the ability to add and edit categories being the primary one, as well as some custom buttons for WLM for statistics and comments, as well as direct links to on-line editing.
In the mean time you can grab the manifest and supporting images yourself, put the .manifest file in the root of your blog and the two images in the images directory under your blog root. This will give you a branded weblog panel;
Isn't that nice?