TypePad has introduced Rich Text Editing and integrated Spell Check.
Frankly, the Rich Text Editing feature needs more work. In the few seconds I've been editing this post I've already come across two bugs -
1) Holding down the Ctrl key and clicking on an arrow key doesn't facilitate block movement / selection as you would expect.
2) If you edit the text of a hyperlink you get stuck in the hyperlink. Maybe I just need to read the instructions but I would expect a more intuitive way of 'getting out' of a link edit besides doing a hard return.
Of course I'm using the Firefox browser so your mileage might vary on Internet Explorer but Firefox is supposed to be supported aswell. Not that it really matters to me too much - I've been hand coding HTML for so long now that I'll stick with that for most of my blogging. Still, having the WYSIWYG option will be useful for photo placement at least.
As for Spell Checking, I'll most likely stick with the SpellBound Firefox extension for that purpose.