Beta 2 of Office 2007 is getting closer (expected this week?!) and one of the latest feature additions is blog support in Word 2007.
You can use Word to either create new posts or edit existing ones and then hit a publish button. They promise it will produce clean HTML rather verbose Word HTML. Beta 2 will support MSN Spaces, SharePoint 2007, Community Server and Blogger but more providers will be added before the final product ships.
Refer to Joe Friend's post for more details about Word's blog support including screen captures.