Generally, feed statistics - the account of how many subscribers a blog has - don't jump around too much. Subscribers don't tend to leave en masse. Over the past few days, I've seen the reported numbers from FeedBurner for this blog drop by 60%. This seems like nonsense to me. In addition, I've been getting quite a few emails and comments telling me that the feed is no longer valid, that it contains 'div' elements and so on (this may have been due to my attempt to embed Gigapan images, though I'm not yet convinced of that).
It looks like FeedBurner may be another casualty of Google's acquisition system. Good luck to Jaiku!
I posted recently on the dangers of free systems. Gerald commented that there are lots of free things out there that are great, such as open source software. Open source software is free like someone giving you the blue prints to a car. FeedBurner is free like someone saying: here, I'll give you free fuel for your car. Then, one day you are driving to work and find out that the fuel is actually not gasoline but orange juice. It's still free, but it doesn't work.
So, FeedBurner - what's up? I'd certainly appreciate some information about any radical changes that may have been implemented in terms of how you count things.