The difference in mobile technologies

Yesterday I gave a masterclass about mobile learning, you can watch the dutch video at:

http://www.ustream.tv/recorded/43037579

or participate at the masterclass in dutch at (it’s free! thanks to sponsoring of SURF Academy)

http://portal.ou.nl/en/web/masterclass-ow-131113/

One interesting issue of discussion was the question what different affordances different mobile technologies can offer and how this has consequences on the instructional design of mobile learning. I think this is definitely an interesting issue and if someone knows any research papers on this issue I would be interested to get some recommendations.