How can participants remain connected after a conference?

The DEECD or the Victorian Education Dept in Australia is holding an innovations showcase on May 15th this month. This showcase has two elements
1. Face to face presentations
2. Simultaneous online sessions in elluminate open to anyone, anywhere – local, national and global
A ning has already been set up on the theme of “guide to innovation” in education, with members already registering. Goto Knowledge Bank if you wish to particpate in the online sessions. The organizers want people to stay connected after the conference, especially with the presenters whose ideas they would like to use in their own school, classroom or other facility (eg Royal Children’s hospital) People will have a range of experiences with various web2.0 tools, ranging from NIL to advanced. One of the conditions of presenting is that we maintain contact with those who wish to learn more.
My questions are:-
How do we get obtain their details to connect them to the presenter(s) (assuming they are not capable of dealing with a ning yet)? I am suggesting a google doc and associated survey form embedded on an appropriate website. Could we use their mobile phones on the day to grab the data? Is there an online collection site somewhere? (Remember we are in Australia). Twitter has been suggested but that could also be way beyond many of them. Do you have suggestions? What have you done or been involved in?