FYI data.gov launched in May 2009 after being announced by Obama's CIO in March 2009. This isn't a new effort, it's the continuation of ongoing efforts.

For example: http://ideascale.com/userimages/sub-1/736312/ConOpsFinal.pdf is a document (Dec 2009) documenting the vision for Data.gov, and http://www.whitehouse.gov/sites/default/files/omb/assets/mem... is a memoranda from 2009 that first started requiring the online sharing of major datasets.