Using the Wi-fi at Lotusphere has been a real nice experience so far this year (of course the OGS on Monday being the true test). Coverage is better and the bandwidth seems to have been upped quite a bit. I do find it a bit sad though that the network is still open and unencrypted. Even a passphrase like "Lotupshere" would make security so much better. Why you ask? Why because a place like Lotusphere which is, lets face it, a big gathering of geeks. A worse a big gathering of geeks using social software sites. And using them a lot.
Lotusphere will be a nice place for someone running Firesheep to come in a harvest 5000 accounts in a day or so. I wont let it stop me but I think people should be aware of it. If you are afraid of it I suggest using a tunneled VPN connection to access your accounts.
If you want to learn more about Firesheep see the Wikipedia article or simply search for Firesheep on Google. Also just to be fair - this is a problem, and will continue to be a problem at all conferences or gatherings with open wi-fi hotspots.