This drive to be completely up to date has led to the development of tools that drive instant notification of "matches" to saved queries. Early in Twitter's infancy, one had the option to "track" a word and get instant notification of its being tweeted. But due to Twitter's rapid growth and some infrastructure holes, the feature has long since been dead. In its place has risen third-party tools and products that tap into Pubsubhubbub, a real-time notification protocol powering most of the world's blogs today, and many different content sites.
Among the most aggressive promoters of Pubsubhubbub and real-time notifications has been Julien Genestoux of Superfeedr, an infrastructure for real-time parsing of feeds in the cloud. Superfeedr recently launched a "Track" tool to instantly find Atom-based entries that match keywords pushed to a developer's application.
Chatting With Supertrackr and Tracking Results for Android
One of the simpler and more interesting applications of this tool that I have seen is called Supertrackr. Developed by @Harper, Supertrackr operates within any Jabber-based IM client (or Google Talk), and lets you follow or remove keywords, via something of a command line, and get updates instantly. The app taps into Google's App Engine and Superfeedr to drive results into your chat window as new entries.
Removing Android, and Seeing Updates on Other Keywords
For practical purposes, you probably don't want to "track" popular terms like "twitter" or "android" or "e-mail" because your chat window from Supertrackr would get flooded and you would have new entries before you even acknowledged the last ones. I tried, and it works, as advertised. Operating Supertracker is as easy typing "/track word" to follow a term and "/remove word" to stop. So if you are in a Jabber-based IM client or use Google Talk often, you could be leveraging Supertracker to find all URLs discussing hot topics, or following your company or brand.
Twitter may not have brought Track back, despite Steve Gillmor's insistence they do, but other developers are filling the gap to get us closer to that monitoring utopia of instant notifications on anything from any source anywhere. Check out Supertrackr at http://www.supertrackr.com/ or Superfeedr at http://superfeedr.com.