I can't remember where I saw the list of phones that can use the auth app. I am now back into WoW and believe having one will be a good idea. Can someone please point me into the right direction of where this list is at? Thanks

Also, what cell phone would be the best choice? I know some people perfer blackberrys more then other phones.

This link should help you:

http://us.blizzard.com/support/article.xml?locale=en_US&tag=BNETMOBILE&rhtml=true

The mobile authenticator is free for some phones and has a small fee (.99 cents) for others (Blackberry).