Identifiable data from the 1940 census is set to be released Monday, April 2, 2012.
The two links below provide fun background to the data. The data will be released via the National Archives.
Identifiable data means that family researchers can look up parents, grandparents, neighbors, etc. as long as that person was included in the 1940 census. It will include names, birth dates, etc.
Currently, the data are only indexed by enumeration district, so unless one wants to scroll through all the records for a state, one should use this handy address to enumeration district crosswalk: