COMMENTS
There are a few services working on this, check out the CloudStatus demo from Hyperic at http://www.cloudstatus.com. They also provide this app as a product you can install onsite.
With that said, there is room in this space for more advanced monitoring; just because EC2 is available from Mountain View, CA that doesn't mean it is reachable from New York. Not only that, response times may vary based on geography - I'm not sure this problem will be going away anytime soon.
Interestingly enough, the kind of response to a cloud outage may be quite different from the kind you would experience in a NOC. If cloud connectivity is degraded, an office manager or secretary can call the provider to determine the severity of the outage and the estimated time to correct it. This means traditional tools (Nagios, Zenoss, Cacti, etc.) may not be suitable for this kind of application.
I think Hypernic has a good interpretation already, but there is probably room to improve on this.
Most experienced operations folks that I know understand that monitoring/alerting systems are an essential part of being successful. Insert "tree falling in the woods" pun here.
Implementing in the cloud, doesn't fundamentally change either the problem or the many solutions. Again, most experienced folks that I know with their stuff in the cloud are monitoring it too.
There are a gazillion monitoring services and product that allow you to pay attention to your technology - cloud or otherwise. There are simple solutions that simply ping the front door to see if you appear to be alive. There are also sophisticated versions that allow you to go much further into your stack including some pretty fancy technology specific versions, like mobile that allows you to get all the way to through the carrier and to the handset.
On the cloud front, many of them, Amazon included, already have their own weather report type monitoring of high level trends usually projected on a web page.
So I don't think this is some new problem without ample solutions, nor do I think it is a cloud specific issue.
Maybe what you are really pointing out relating to cloud computing is this...
As cloud computing improves, becomes simpler to magically get stuff done and the audience broadens to include less experienced users that expect more to be included, perhaps they even unknowingly aren't paying attention to this age old challenge.