Blogger adds WYSIWYG editing to its interface and Christopher Jason Wetherell's discusses the usefulness of WYSIWYG editing in the browser (he also provides a more technical note on this implementation).
What you see is mostly what you get.
So, it became evident during testing trials at Google of WYSIWYG editing that a large set of people have learned a minor set of HTML for basic expression needs, and have grown so accustomed to using them that a WYSIWYG mode which didn't easily allow these people to compose using that markup presented large and sometimes unacceptable interruptions to their content creation task. Furthermore, having a place for them to enter a "source mode" only frustrated them further as they wondered where the styling went. You see, some of us know some HTML but not all, and with broader expression available to them, these new-to-them tags presented challenges that were, at times, more annoying to them than if WYSIWYG didn't exist.
One solution, implemented now at Blogger, is to create a mixed-mode enviroment for WYSIWYG where a user can enter rich styling and HTML and have both work. So (as coined by Jason "Mr. Product" Goldman) the result is more of a WYSI-M-WYG or "What You See Is Mostly What You Get" editor.
We believe that is helpfully pronounced "Whizz-ah-ma-wig".
There are some caveats, though... As one who has complained many times about old-school rich text editors, I fingered Midas some time ago for its propensy to generate tag soup. As evidenced by the HTML code on Christopher's posts above (e.g. it's full of
<span style="font-style: italic;">...</span> à la Midas), this kind of rich text editor is not going to do its users a favor on the long term! This said, it's a move in the right direction, and I hope others will follow suit in a way that is more respectful of the semantic/style XHTML/CSS couple.