There are many steps that must be taken to process the indexes, and more were added to increase the quality of this particular index. For those reasons, it will be a few more weeks before the census is fully searchable online at FamilySearch and their partner sites: findmypast.com, and Archives.com. Check out the FamilySearch blog post Paying the Price for more information about the processing. However, if you don't want to wait. Ancestry.com announced today that the 1940 census index is complete on their website and free to search until December 2013. This index was done independantly from the US Census Community Project and may be different. If you don't find the household for which you are seeking on one site, always check the other.
But what if you want to keep helping making records available online to genealogists everywhere? Don't despair. The next community indexing project From Sea to Shining Sea has already begun! This is an exciting new project of Immigration and Naturalization records. These projects are available in the download batch list now with the project name beginning with "US (Community Project)" (you can sort the list by Project Name by clicking on the column header.) Visit the FamilySearch blog post From Sea to Shining Sea for a list of projects under this category, some interesting immigration historical facts, links to FamilySearch wiki articles on Immigration and Naturalization, and links to free research courses on using immigration and naturalization records.
If you haven't participated in the indexing program and have been curious about how it works, visit the same blog post to download and install the program, register for a familysearch account, and start indexing. You can always email our society indexing administrator at email@example.com if you have any questions or need some one-on-one indexing training.
Keep on Indexing!