We've built a site that is sort of a web version of motion, see http://sensr.net for details. The idea is to monitor cameras but to use servers in the cloud to do it rather than a computer in the home. In our approach, the cameras send images directly to our servers (via FTP).
The sensr.net site focuses on:
o Motion detection
o SMS and email alerts
o Image archiving
It occurs to me that users on this list might be interested in our service (shameless plug here). But we could also integrate with the motion software. Since we take FTP images, you can create a camera on the sensr.net site and have the motion software FTP images to sensr.net. This would allow you to monitor your cameras without having to open firewall ports, etc.
Used in this way, the sensr.net site is also a form of backup. Should the computer running motion be stolen or destroyed, the images uploaded to sensr.net would still be there. (We use Amazon S3 to store images and Linode servers to process them.)
When you add a camera on sensr.net, it can be private, public, or shared among your Facebook friends. For a list of public cameras, go to http://sensr.net/cameras and take a look.
I would love to get some feedback from the motion users. This group obviously has a lot of interest and expertise in our domain, so please excuse the shameless plug!
PS We've also setup a Google Group for sensr.net related discussions.