Most people use wireless access points to provide access to the internet, of course, but often there are situations where you can’t get access, or access fast enough to be meaningful. (ie. a dialup connection quickly gets overloaded with all but the lightest activity.)
I suggest that AP firmwares be equipped with local services that can be used even with no internet connection. In particular, collaboration tools such as a simple IRC server, and a web server with tiny wiki or web chat application. Of course, there are limitations on flash size, so it might be you would make a firmware for some APs which rips out the external connection stuff to make room for collaboration.
There are a variety of open source firmwares out there, particularly for the Linksys WRT54 line of APs, where these features could be added. There are a few APs that have USB ports where you can add USB or flash drives so that you have a serious amount of memory and could have lots of collaborative features.
Then, at conferences, these collaboration APs could be put up, whether or not there is a connection. Indeed, some conferences might decide to deliberately not have an outside connection but allow collaboration.