Yikes, not sure if this is such a good thing or rather something that could be seen as a RSS exploit. Eh, regardless I suspect that it will be used for good and bad. Too bad for the FeedBurner users I guess.

Want to know how many subscibers are there to someone else’s RSS feed ? It’s possible to find the readership if that site is using Feedburner to syndicate content.

Here’s a simple text replacement trick to find the number of people that have subscribed to any XML feed that’s powered by Feedburner provided the feed publisher has enabled FeedCount.

Feeds on Feedburner have an address like feeds.feedburner.com/labnol. All you now need to do is prefix the feed name (labnol in this case) with ~fc/ so that the new URL looks like feeds.feedburner.com/~fc/labnol

You’re done. Just click on the new URL to see the count of RSS subscribers. It points to an graphic image (in GIF format) which you can also embed in your webpages as you see below…. Source: Digital Inspiration