According to information now posted at FamilySearch Indexing, the 1916 Canadian Prairie census will be available free to patrons at Family History Centers as of 14 May, 2009 through Ancestry.com. I think we can assume that both the index and images of census pages will be available, pretty much as now offered on Ancestry.com's subscription site.
This 1916 census covered those in the provinces of Alberta, Saskatchewan and Manitoba. The census pages were indexed earlier by Family Search volunteer indexers under an agreement between The Generations Network (TGN - often known as Ancestry.com) and the Church of Jesus Christ of Latter-day Saints.
This winter, the 1916 census images will be available free on-line at Library and Archives Canada as well. However, according to agreements apparently made between Library and Archives Canada (LAC) and The Generations Network, no nominal index will be available free at LAC until the summer of 2011.
And very soon, indexes and images of the 1861 and 1871 Canadian national censuses should be available on Ancestry.com and sometime this summer, images of both those censuses with an index for each should be available free at Library and Archives Canada.