Two years from today – April 2, 2012 – the National Archives will release the 1940 census to the public. According to the National Archives website: http://www.archives.gov/genealogy/census/1940/general-info.html , the plan is that the census will be digitized and available at the Archives and online on that day. Note that April 1 will be a Sunday, so the 1940 Census won’t be available until the following day. I don’t see anything about indexes…
I don’t know whether Ancestry.com, Heritage Quest, Footnote, FamilySearch and others will be able to enter into agreements with the Archives for digitization and/or indexing before the legal release date. Commercial digitization and indexing of the 1930 census began upon delivery of the microfilm – following the April 1 release date in 2002.
Thanks to Joel Weintraub for bringing me up-to-date on the info. at the National Archives site.