I imagine you'll be seeing a ton of these messages around the internet for folks using Community Server.
The Windows Live Writer doesn't exactly integrate 100% yet, so what will happen is that these temporary post messages will be left out there.
What happens, is that when the Windows Live Writer client tries to download information about the blog target (styles, etc.) it creates a temporary post which it uses as a template for this information. With Community Server-based sites, it creates this template but currently fails the download of style information and it can't clean up the post. This might be because the URL for Community Server in the blog account within the tool might not be right (I tried the control panel and I tried the metablog.ashx).
Be interesting to Google(MSN Search) it to see how many times it comes up over the next few weeks.