I forgot that I already blogged about the work that Jake Savin (and others?) had done earlier in the month to get Radio and Manilla hooked up to Gecko's content editable features.
Bob Stepno's "Firebird Browser Speeds OS-X Weblog Editing" post gives some demonstrations and also notes a few Mac bugs (I think we've got most of those fixed for the next Firebird release.)
Is WYSIWYG editing in Mozilla or Firebird the only WYSIWYG available for bloggers on Mac? Does MacIE not have the winIE editing control? What about Safari? Does it offer this feature?