Hello,
As I understand it Wikimania intends to make reasonably heavy use of IRC. In any case, having more than twenty-odd connections is not permitted on freenode without getting special authorisation. They will be quite happy to give this - they just need a list of the IP addresses the conference will be connecting to the Internet from.
Unless this gets done there will be problems, so please, let me know those IP addresses and I can get it sorted out :-)
Thanks,
[[m:Sean Whitton]] Liaison between freenode and Wikimedia