Over the last years Felix looked at how mobile phones can enhance the shopping experience in the real world. In particular Felix compared different identification techniques (e.g. text input, bar code, nfc)  and at mapping the design space for product recommendation systems on mobile devices . We had an interesting discussion at the PhD defense and I think we will see many products and services popping up in the future.
Being in Zürich I took the opportunity to see more of Florian's group. There are a lot of exciting projects going on, see their Wiki for details. I looked especially at the work on mobile platforms and public displays. The AppAware application (http://appaware.org/) on Android has an amazing potential. Users share events (what applications they are installing, removing and updating) together with their location. It is just amazing to see what people around you install - and being close to ETH you see events every second.
 Reischach, F., Michahelles, F., Guinard, D., Adelmann, R., Fleisch, E., and Schmidt, A. 2009. An Evaluation of Product Identification Techniques for Mobile Phones. In Proceedings of INTERACT 2009, the 12th IFIP TC 13 international Conference on Human-Computer interaction: Part I (Uppsala, Sweden, August 24 - 28, 2009). LNCS, vol. 5726. Springer-Verlag, Berlin, Heidelberg, 804-816. DOI= http://dx.doi.org/10.1007/978-3-642-03655-2_88
 von Reischach, F., Michahelles, F., and Schmidt, A. 2009. The design space of ubiquitous product recommendation systems. In Proceedings of the 8th international Conference on Mobile and Ubiquitous Multimedia (Cambridge, United Kingdom, November 22 - 25, 2009). MUM '09. ACM, New York, NY, 1-10. DOI= http://doi.acm.org/10.1145/1658550.1658552