Webmaster World's PubCon and Search Engine Strategies Chicago fall on the same dates this year - Today through Thursday.
Many in the industry have had to choose between one or the other. The staff at Yahoo is splitting their staff to attend both, as are many others.
I was in Chicago several years ago for SES. It's COLD this time of year, which no doubt had some bearing on a few 'choices'.
In any event, for those like me, that are staying here on the east coast, Search Engine Land has provided some resources for watching coverage on both events on the web here .