Hi Krishna - all data sets will be available at http://data.cityofboston.gov. The newest data sets are being posted there on Saturday when the challenge begins, but there is also a lot of data already on the portal for you to peruse and brainstorm around!
I will add that we are working on spatially enabling some of the Socrata datasets used in the hackathon. The data will be available via geoservice RESTful endpoint, geoJSON RESTful endpoint, KML, shapefile and other formats. Find them via the spatial Open Data portal here: