Haven't heard of any method unless you run something like StatPress plugin or have your RSS going via FeedBurner.
For the life of me, I can not remember (maybe I never knew this?) how to find how many people have subscribed to the rss feed of my blog.
Is there a way?
All my searching led me to one thing:
Plugins or third party services.
Now to figure out the best way.
I've always used FeedBurner, one click access to all your stats and then some.