Hi Mike,

we have some experience from the 2005 Museum Night in Amsterdam, where we used 2d barcodes for the first time in a few museums. The experiment did not pass the test of taking pictures with your mobile phone at night , and was not repeated. Although we are in touch with Dutch operator KPN about mobile projects, and would love to look into mobile applications.
I have also been in touch with Ulla Mutanen from Helsinki, from ThinkLink, and she might have more experience with this. Or perhaps the people from Aula (http://aula.cc) might be able to help, since they are involved with Nokia.
Hope this is of any use to you.

All the best,

Juha