It will be about Google Apps Script, a fairly new and powerful web automation technology that was actively developed over the course of last year. We will have a guest speaker from Switzerland, Nicolas Garnier, Google Developer Advocate who will make an introduction to Apps Script and answer all sorts of questions you might have about Google Apps.
To get a feeling of Apps Script's capabilities check out the recent blog post describing a few projects from the similar event in New York city like Minesweeper inside Google Spreadsheets and Wolfram Alpha query service.
UPDATE: And the winner is Gogles, a Go game inside Google Spreadsheets. You can view the source on github or try the script from the gallery. Thanks to all participants!