All sorts of caveats apply here. All iPhones are counted as one model, while Canon’s DSLRs are separated into different model categories. Flicker is focused in US, iPhone has Flickr upload apps, etc, etc. Still it is impressive that the iPhone is now the number one camera on Flickr. This has been in the works for awhile.
It is also destroying all of the other cameraphones, naturally. One has to wonder how a camera-focused iPod touch will do comparatively.