It's a great idea -- which is why it has been done so many times. Your competition slides are not a good indicator of how much competition is out there. Pingdom, for example, is not really a competitor, but Clicky, ClickTale, etc. (not shown) are.
Seems well worth a shot, especially with server down alerts included. No mention of ssl? Your final link in the PDF points to the memcached site. Pricing would also be key to me; bootstrap-friendly prices would be ideal, including a free trial.
