Love the new dialogs. It will make plugins look feel less hacky.
Just figured out the usage and tested out both with this:
sublime.message_dialog("Done.") if sublime.ok_cancel_dialog("Do it?") else sublime.message_dialog("Not done.")
And it worked great! Thanks for this addition. I like how I don't have to point it to a function with the confirm dialog; it is nice being able to process it right at the moment it is invoked. It makes things much cleaner to code for.