I found the following WYSIWYG editor for Wordpress that was compatible with WPMU: http://mudbomb.com/archives/2005/02/02/wysiwyg-plugin-for-wordpress/
The only issue folks, is the image manage dosn't work properly because it can't get write access to the folder where it wants to browse and place uploaded images. The image manager was the only reason I wanted to use a different WYSIWYG editor in the first place!
It seems to me all this needs is a trick to change the upload path to the blogs.dir equivalent. Any takers? this could mean a big deal to our frustrated artsy fartsy types.