I'm assuming that you are talking about a command line program. If my assumption is correct, then they'll never, EVER, will be an Terminal app for iOS. At least not one available on the app store. Of course there are ways to get it onto iOS, but I doubt Apple would appreciate me telling you how to do so.
Yes, there is are Terminal apps for iOS available through the AppStore. There's nothing dodgy about them.
One of the best apparently is "Prompt": http://www.panic.com/blog/2011/04/introducing-prompt-ssh-for-ios/