Long story short, I came up with BlogTalk. An IBlogExtension that reads a blog entry to you or optionally saves it to a wav file.
I particularly like the inflection and pauses the speech agent interjects. Makes me wonder if I'll start writing for maximum spoken clarity.
Obvious improvements await, but for 20 lines of C# and an easy xslt, it is pretty cool.
Watch this space for a freebie release soon.