The App that enables you to throw out an SMS in about 5 seconds is here.
It will be in the App Store any minute now.
It's only $0.99.
The best way to use it, is to place its icon next to the iPhone's green/white messaging icon. Then, if you need to see conversations you can just switch to the standard app. If you need to be quick, you use the SMS-Fast app.
I've been using it for a while now. Make sure you add some useful messages and use the wildcards when necessary.