Brilliant email from Amex about offers included this, to transition people's cell phone CC to their Amex. So, so, so smart.pic.twitter.com/p8hi6BiGGi
You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more
You need to deduct the cost of service from the interchange fees... reward points even if nothing else.
i recall that AMEX charges merchants ~6%, 5 if you only accept amex.
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.