With the debut of the 3G model, Apple’s iPhone surged to a commanding lead among camera phones used at Flickr. These statistics from Yahoo cover the last 12 months.

(Credit: Yahoo)

Right now the iPhone is in a virtual tie with Canon’s Rebel XT and Nikon’s D80, two SLRs whose popularity is waning with the arrival of newer models from the dominant makers of such cameras. Only Canon’s newer Rebel XTi outranks the iPhone.

Though the trajectory is clear, there are caveats. First, Flickr measures popularity on the basis of the number of users who’ve uploaded a photo on a given day. In other words, the camera used by a person who uploads one photo a day will fare better than one who uploads 100 pictures one day a month. Second, many camera phones don’t identify themselves to Flickr, so their use isn’t logged. Last, these statistics fluctuate daily, and who knows what kind of anomalous behavior is going on during the holidays.

The total number of photos uploaded from the Rebel XTi is about 51 million, compared with 5.8 million for the iPhone. However, there are nearly 3,000 people uploading daily from their iPhone compared with about 6,500 for the XTi.

My guess is the iPhone’s better-than-average network abilities are responsible for the prominence. For the same reason, iPhone users also use Google Maps and other online services more than most mobile device users. The BlackBerry is good at e-mail, but the Internet has other attractions.

What’s more interesting is extrapolating from the trend. Certainly the iPhone’s image quality doesn’t hold a candle to even old point-and-shoots, much less new SLRs, but the phone taps straight into the social features of Flickr–the ability to photographically share with friends and family what’s going on in your life, for example. There are innumerable expert photographers at Flickr, but it looks like the yet larger herd of ordinary snapshooters are going to leave them in the dust once liberated with the ability to post pictures at will.

I sent my iPhone photos to Flickr using the site’s upload-by-e-mail service (see Yahoo’s instructions), but there are several iPhone applications that will do it for you if you prefer. Apple’s photo e-mailing software scales photos to 640×480, but I don’t mind, given feeble image quality and the unlikelihood that these shots will ever make their way beyond a computer screen.

Stephen Shankland covers Google, Yahoo, search, online advertising, portals, digital photography, and related subjects. He joined CNET News in 1998 and since then also has covered servers, supercomputing, open-source software, and science. E-mail Stephen.