I'm just having a fiddle with Windows Live Writer to post a message to my blog. I have used a Word plug-in occasionally (and have never bothered with emailing in posts - I always figured it would be useful if I had a Blackberry!) but usually stick to logging in directly through Blogger (or Blogger Beta as is the case at the moment).
It hasn't managed to download my styles, but hey - it doesn't matter that much, I'll maybe try again later.
The interface is nice and clean:
It's easy to insert images, and format them.
Technorati tags were easy to drop in (and other tagging providers - Flickr, del.icio.us - are also available).
You can also add in Google Maps and links are easy to drop in (also with "rel" attributes). I'm looking forward to microformat insertion - as I believe that may also be possible. My only negative so far is that they need to add "technorati" and "flickr" into their spell checker index - seems daft that they throw up as mis-spellings when they are used by the application itself.
[UPDATE] When trying to post this message, I was unable to publish it. A little research indicated that you need the latest update for Live Writer to work with Blogger Beta. I've also tried to install the Flickr third-party plug-in which is not working at present, but I'll keep trying with that.