I was just a member of the panel during a discussion which took place at the Medientage in München.
We were asked to come up with ideas around what could help a typical attendee. Beside other topics we discovered that one thing was omnipresent: Social Networking.
It is certainly true that conferences are not only to consume information but also to network with peers. Maybe the later is becoming more important over time.
I never saw a conference doing a really good job here. Why? Because there are two contradictionary wishes: One is to be able to network and do this efficiently. The second is that not everybody is willing to show her or his entire information to whoever is also part of the network.
While efficient networking can be done by Xing or Facebook or whatever you prefer the second is harder. You can rely on accidental meetings and then exchange business cards. But this is not efficient.
I think the social network must provide this kind of privacy. My idea is as follows:
You register yourself to take part at an event and provide information towards the social networking system. Here you can allow the system to present your contact details to everybody (which might be of interest for sales personal). This is an opt-in so the default is nobody can access detailed information.
Then one can search within this profiles but only get displayed the profile information. If this profile seems of interest try to contact this person. Here the social network sends a message to the human being behind the profile showing your profile and ask for the will to contact (and how).
The difference towards general social networks is that during conferences physical meetings can take place and the system should support here. It can be very efficient here because it might knows the schedule of the persons involved.
Also it can provide some offerings based on the sessions one visited who might be of interest.
Maybe a nice question to be solved on Windows Azure...