There is this old and upsetting thread in the Bing Forums about how Bing handles the canonical tag. The thread is filled with misinformation. Matt McGee's post at Search Engine Land a week ago says it clearly.
Bing says it's still working on supporting the canonical tag on a single domain, and suggests webmasters should rely on other means to manage duplicate content.
You got that right, 11 months ago, Google, Yahoo and Bing announced support for the Canonical tag. As far as I know, only Google really uses it and they even added cross domain canonical support this month. Where is Bing at this? Well, in the next several months they hope to support a single domain use of the canonical tag and hopefully soon after the cross domain support. So it would have taken Bing over a year since they announced support of this tag to actually support it?
I am not too upset about that, to be honest. What I am more upset about is that official Bing support representatives are pretty much lying in the Bing Forums. Brett Yount, the Product Manager of Bing Webmaster Center said:
accourding to our blog post, http://www.bing.com/community/blogs/webmaster/archive/2009/02/12/partnering-to-help-solve-duplicate-content-issues.aspx, the canonical tag is used as a hint only.
No, it is not used as a hint or anything. It is not used period, not yet. Maybe in four months, but not yet.
Forum discussion at Bing Forums.