CMAJ, which has been an open access journal since 1995, will cease being so in January 2010, when some content will be restricted to subscribers.
Here's an excerpt from the "No Longer Free for All":
The harsh economic reality is that CMAJ, like many others in the publishing industry, has experienced a considerable decline in advertising revenue over the past two years. This loss necessitated an extensive examination of other business models to adequately address today’s economic challenges.