Yes, but that's the easy part, isn't it. Anyone can write a quick polling app based on RSS. The hard part is (off the top of my head ...): o Putting together

Yes, but that's the easy part, isn't it. Anyone can write a quick polling app based on RSS. The hard part is (off the top of my head ...): o Putting together a UI that people can use and will like. Notifications should be quick and easy to set up. They should be noticeable enough to work, but they should not cause problems with existing workflows. And the whole system needs to be easy for the user to understand. o If a new protocol: get sites all over to use it. If an existing one, figure out how to wrap around it nicely (extract and display the right info, etc.). o Integrate this with non-RSS stuff, like the things that Growl does.