Google exposed the number of Google Reader / iGoogle subscribers to a feed in the crawler's user-agent and in the Webmaster Console, but that's only useful for your own feed. What if you want to see how many subscribers Google Operating System has?

Now you can see the number of subscribers by searching for the feed in Google Reader: click on "Add subscription", enter the name of a blog and you'll see the number of subscribers next to each (hopefully relevant) result. This number includes everyone who subscribed to a feed using Google Reader, iGoogle, orkut or other Google properties. The subscribers aren't necessarily active.

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