You Can Post a Photo on Twitter via MMS

Starting today, you can share photos on Twitter by including a photo in your text message. It's simple: just enter the text of your Tweet as you normally would, attach a photo to the message and send to Twitter.

Twitter has announced that you can now post photos to the service via MMS.
This feature is currently available with the following carriers*: AT&T, Verizon Wireless and Cellular South in the US; Vodafone, O2 and Orange in the UK; Vodafone Italy; Rogers Communications in Canada; VIVA Bahrain; and, TIM Brazil. We'll continue to work with more carriers to enable their customers to share photos via text message.

You can find the "short code" number used to message Twitter here