It's run by a friend of ours who used to work at Sitepoint and was frustrated by the limited options for good, affordable, distributed monitoring. He's been running it for over 2 years and is growing fast.
It's a great service and recommended as a YC-style startup worth supporting.
Simple but it works.
1. dwatch http://nubyonrails.com/articles/2006/03/29/surviving-rails-1...
2. a PHP script that accesses a URL on the other server; if the server does not respond as expected, it sends me a SMS and emails the server admin
I use a free uptime service to make sure that my servers are reachable: http://uptime.openacs.org/uptime/
Many of these systems use rrdtool and even though I've used that tool directly before, with Cacti at least its a bit tricky to get familiar with the way the gui and the different templates are interconnected. The look and feel sure does seem polished though.
If anyone wants an invite to NewsCred, shoot me a mail: shafqat at newscred.com. Its not much, but thought I should say thanks!
in addition we use monit and then finally we use wormly as a catchall