Conversely, if you’re building a real-time web service, think not only in terms of the value it provides to producers of content, but also in how you can make it valuable for the consumers of content. “Find out that the balloon boy news was a hoax, within a minute” is not valuable enough to most people to warrant the constant interruptions. If you don’t provide some kind of tangible value to people, your service probably won’t be successful in the long run, however trendy and sophisticated the technology.

Yes! Fully concur. Real-time notifications are a tool, like anything else, and going full-bore with real-time for everything is a serious mistake.