Convenience apparently trumps quality when it comes to uploading photos to Flickr, because the iPhone is currently neck and neck with Canon's EOS Digital Rebel XTi as the most popular camera on Flickr.
Yesterday Electronista reported that the iPhone had taken the lead as the most popular camera on Flickr, but the current stats show that the two devices are neck and neck once again. It is presumed the sudden spike in iPhone uploads is due to the launch of the iPhone 3GS, so it is probably only a matter of time before the iPhone takes the lead for good.
The stats are a tad misleading, however. You must not only take into account that most people have their iPhones readily available for photo taking at any given moment along with the ability to easily upload them, but also that Flickr lumps all iPhone models together. That would be like pooling all of Canon's Digital Rebel cameras together. Even after all of this taken into account, it's still quite a feat.
On a related note, the iPhone has been the most popular of the identifiable cameraphones for Flickr uploads for quite some time as indicated by the chart below.
