I spent a bunch of time getting Leopard installed and set up on my mac to find out what goodies it would bring to the iPhone. It looks like syncing notes from the iPhone to Mail might have been pulled just before it was ready, or that it's going to come in a future iPhone update. When I tried to change the default font in an edited note from Marker Felt to anything else, I'm given this warning message:

"Convert this note to rich text format?
Changing the style or formatting requires that this note be converted to rich text format. Rich text notes may not be editable on iPhone and other devices."
The language is there, as you can see above. Based on the language that I see above, I think it's safe to assume that it should be available soon.

And in other news, it looks like Apple hasn't made up their mind whether or not we'll be able to edit rich-text notes in the future. The fact that there's a warning at all indicates that we should be able to edit notes on the computer and have them sync to the iPhone.