Section 2 of the Canadian Holidays Act states the following:
Canada Day
2. (1) July 1, not being a Sunday, is a legal holiday and shall be kept and observed as such throughout Canada under the name of "Canada Day".
When July 1 is a Sunday
2. (2) When July 1 is a Sunday, July 2 is a legal holiday and shall be kept and observed as such throughout Canada under the name of "Canada Day".
R.S., c. H-7, s. 2; 1980-81-82-83, c. 124, s. 1.
In other words, Canada Day is on July 2nd this year (2012).
Reference: The Holidays Act on the Canadian Justice Department website at http://laws-lois.justice.gc.ca/eng/acts/H-5/index.html (last checked 2012/04/23).