Unwanted by some. This article from the NYT observes that many activists single out production from oil sands when it comes to environmental impact, noting that a recent RAND Corporation study estimated that oil from the oil sands generates about 10 to 30 percent more greenhouse gases than conventional crude. Still, as the article points out, however, there are energy security benefits.
[Update: There are similar issues raised in the U.S. regarding oil shale development on public land in Colorado, Utah and Wyoming, according to this article from the AP.]