Well, here's the thing. From having worked at Y!Mobile, I know that carriers pull this sort of thing often; they'll change the way their MMSes are formatted, what you can send in an SMS, or whatever, and then not really let anyone know because gosh, aren't people just sending photos to other phones on the same carrier? So they change stuff, our stuff would break, and we'd hear about it too late to prevent any noticeable period of not-workingness. We'd be able to fix it, but that took an engineer or two out of their current task rotation and all that entails... I imagine Flickr doesn't have a dedicated mobile person to watch these things. But then again, it'd be nice if the carriers had a mailing list developers could subscribe to, to be notified when the carrier changed how something work. As far as I know, they don't.

Also, this is why I hesitate whenever someone says "Oh, this service would be better with SMS integration, and a shortcode, blahblahblah..." Setting all that stuff up isn't quick-and-easy, and there's no free service (that I know of) that acts as an incoming-mobile-gateway parser. That stuff costs. And doing it yourself? No standards, mo' problems.

Okay, I checked with a source and I stand corrected: there are developer networks. But they might not be that good. So it's still a pain. Some quotes from my source: "the carriers are not very nice" and "they mostly have to be backwards compatible so I can't imagine they'd just suddenly stop supporting older formats."

I've been unable to send photos to flickr on Sprint for the past week (although I've only tried twice). So you're not alone.