A couple weeks ago we asked if the canonical tag works well on Google. Since it is poll week, and I am offline, I figured I post the results from the poll.
We had just under a hundred responses and I am surprised to see as many as 14% said the canonical tag does not work for Google. Most said it does work, but 14% said it does not. There must be some type of bug for those 14%?
Here is the break down of the results:

Do you agree?
Forum discussion continued at WebmasterWorld.

Comments:
Matthew Diehl
03/31/2010 01:44 pm
I missed this poll but I have only seen positive outcomes when using the Canonical Tag with Google. Chalk up another "Yes, Works Well" from me.
Martin Greenwood
03/31/2010 05:06 pm
Wow 14%... I think it works, I have it on all my sites and put it on all the ones I work on, it seems to help, especially on the sites with news pages and different county versions. Also works on the mobile version of the website...
Renaud JOLY
03/31/2010 06:44 pm
It works. And it's dangerous if wrong url is used. I learned this with one of my websites at the beginning. SEO Manager - France
Jaan Kanellis
03/31/2010 08:40 pm
I think those that say it doesn't work are seeing issues as in vBulletin forums were you can have 4-5 different versions of the same piece of content.
colin mcdermott
04/01/2010 06:16 am
Having a debate at the moment about using the <base href tag> versus Preferred Domain in Google Tools? So many opinions.
Bill Sebald
04/01/2010 05:50 pm
I still see a lot of dupe content on big sites that have a good implementation but less traffic coming from those dupe pages. That tells me their not getting served. It's a safe assumption that Google will still show the dupes when pinged, but serve them much less with the canonical tag in place. I know it worked on one of my small sites, which makes a sense thinking about how crawl depth works.