Photobucket allows photo sharing by students to a private mobile address. The classroom teacher needs to set up the account and give the students the address so they can submit pictures and messages to the address.
Flickr allows students to take pictures and send them to a private space online. For example: A homework assignment for 4th grade mathematics students requires students to take pictures of different polygons they see in their everyday lives and instantly send them (along with a short text message describing the type of polygon) to a private space online. The next day in class the teacher can open the private space and use it to illustrate polygons and their connection to students' lives, leading to a lesson on how to measure these polygons. Both flickr.com and photobucket.com are sites that would allow this type of sharing. Both have a private mobile address that can be used on any mobile phone; the teacher just needs to set up the mobile account and give the students the address.