I hope that this is of interest for you and may start some interesting discussions during the face-to-face meeting next week. The following link points to a Website of the 'Big Data in Geographic Information Science Panel 2012' which focused on semantic heterogeneity. It contains 97 minutes of video recording as well as all slides from the panelists, some of them active here at EarthCube. Unfortunately, the audio quality for the first part of the panel is low but gets clearly better during the discussion phase. Downloading the slides helps in addition. The page also contains a list of related events, for instance a workshop on 'GIScience in the Big Data Age' that will take place in Fall 2012 and is co-located with the GIScience 2012 conference, as well as links to upcoming and previous GeoVoCamps on developing geo-ontologies.