Yes, I know.
April 2, 2012 seems a long way off.
But if you've lost as many ancestors as I have between 1930 and 1950, you're getting anxious to start digging into the 1940 US Census.
The National Archives and Records Administration (NARA) has now posted their 1940 census enumeration district maps online so that we can all get started figuring out exactly which EDs we're going to need to search when the 1940 census is released next spring.
To view the maps, go to http://arcweb.archives.gov/arc/action/BasicSearchForm
In the SEARCH box enter 1940 Census Maps [county name] [state name].
For example, I entered 1940 Census Maps Hickory Missouri and was rewarded with two results. One of them has a small symbol to the left of the title that indicates "Digital Copy Available." Clicking on that first title takes me to a page with 4 tabs--Details; Archived Copies; Digital Copies; Hierarchy.
Clicking on Digital Copies rewarded me with 4 maps of Hickory County, each marked with the ED numbers for the 1940 Census.
If you've got people lost in US cities in 1940, I'd definitely recommend starting now to identify the probable enumeration districts they were in. Going from city directories to maps can be tedious.
There's no guarantee when indexes to the 1940 census might be made available, but we do know that NARA intends to release the digital census page images on April 2nd, 2012.