We're not exactly lacking in ways to share a photo on Twitter these days, but one key area that has been left behind is the venerable text message -- which is pretty important for the millions of people that don't have smartphones. While tweets via text have been possible since day one, Twitter has only just now opened up the ability to post a photo via MMS. That service is only available on some carriers initially -- AT&T, Verizon and Cellular South in the US, Vodafone, O2 and Orange in the UK, and Rogers in Canada, plus Vodafone Italy, VIVA Bahrain and TIM Brazil -- but Twitter says that it's working to bring the feature to additional carriers. Actually sending a photo via text is as simple as you'd expect (just attach it to your message and send it to the appropriate number for your country), but you'll of course have to be aware of any additional charges your carrier might impose.