Blogo, which was discontinued earlier, is back again. If you are on a Mac looking for a blog editor app, you should try it. You can download the beta for free at:
There is also a cross platform solution called BlueGriffon that looks promising.
My current recommendation and favorite is Blogo.
Easily publish text, images, videos, slideshows and more.
With a simple, intuitive interface and support for Wordpress, Blogger, Typepad, Typo, Drupal, Joomla, and Expression Engine, Blogo is the best
way to maintain your blog and spread the word with Twitter, Ping.fm and other supported services.
It also supports Twitter.
The closest to WLW would be Ecto, but active development seems to have stopped.