Caterina fake of flickr has a piece on Container housing This is a fantastic use for them as not only do they look cool, but they could have a very relevant use in the 3rd world. See Squattercity and you will see a projection on 3 billion! people living in shanty towns by 2050. I think you could probably break the issue down into two distinct parts. Prefabracated living unit design where you have the need for shelter and disaster relief (see future shack by Sean Godsell), and maybe the area of greater need where there are squatter areas some of which are well established and shelter is not the top priority, but where clean water is. Could you manufacture inside a container unit a water filter/treatment unit which could service say a shanty block without need for any further infrastructure? What would it need to do- Filter and rainwater storage system?, store (probably not practical) or partially treat waste before returning it to the local system so as not to pollute any ground water and soil. Any power needed could run off solar panels in the roof. It would basically be a communal tap and toilet area , with maybe a small office to use as a base for mail, internet and other outside services if possible could also be provided. You could link them together also providing a kind of build city infrastructure that is relocatable and almost entirely above ground. A new competition Living Box is running until 31.12.2005 is calling for architectural designs for Prefabricated living units and the website also has some great resources of designers who have done some work in this area. I particularly like guerilla homes as it advocates different ways for peoplpe to inhabit space in different environments.
Standard containers come in three sizes: 20′ x 8.5′ with a capacity of 1170 cft 40′ x 8.5′ with a capacity of 2385 cft 40′ x 9.5′ with a capacity of 2690 cft
other useful links: fabprefab . cargo architecture . shipping containers . shipping container architecture . sean godsell in the guardian . sean godsell . photo is from mmw