if you were to ask siri to spell a word can it do that?

Siri is only on the iPhone 4S. It will bring up the spelling in Wolfram Alpha and display the answer. It won't read the correct spelling to you.

Just say the word to Siri. She should say, "Sorry, I don't know what you mean by '[word]'." So not exactly the answer you're looking for, but it will still include the correct spelling in her response.