What's Happening To The Popular Camera On Flickr?

Since one of our main focuses is Digital Camera Reviews, we regularly look at the popular cameras owned by users of Flickr and we've blogged about these popular cameras (and their ProductCritic Scores) in the past.

I was surprised when I recently looked at the charts on Flickr and noticed a distinct drop in the use of the most popular cameras. Is there a simple explanation for this? Are people just replacing their cameras with newer models and those models have not shown up on the popular charts yet? Are they switching to other brands that also don't have enough market share yet to show up on the top lists? This is happening for both DSLR's and point and shoots though.

Anyone think they have an explanation?