Colan is right about .Ca last I checked.
But something I discovered last week and have not had time to share yet, is that all the different datacenters I've found still show the OLD algo. I have a ton of them, but am only sharing one so doors don't get slammed shut.
HTML:
http://74.125.224.97/#q=seattle+chiropractor
You can just copy the IP above and add your KWs or copy the whole string and replace your KWs w/ + sign.
So if you check that SERP above, using that IP it almost exactly matches my PRE-pigeon screenshot here.

(Oops sorry, the red text at top is misleading now. I added that the day Pigeon hit and meant from 6/22 - til Pigeon hit, those had been the results.)
David Lee and Matt Brown were in PRE-pigeon for a long time. NEVER since pigeon hit, unless you search via .CA or one of those old IPs. ALSO all tracking software that sends me screenshots of the SERPs are showing me the old PRE results too.
So what I think is happening and the reason the SERPs are switching back and forth so much - is I think there are 3 or so new versions of the algo or one algo with a few different elements... but they are sitting on a 3 or so new datacenters and Google is switching datacenters back and forth doing AB testing or something.
We had a Huntington Beach Chiro here saying one day she's B and the next she's totally gone. Then I just helped a guy on the G forum that said Google is rotating his SERPS. One day he's A, the next B or C. The next A.
I think she's rotating datacenters that different versions of the algo are on.
That's my latest theory anyway.
TECHY HELP NEEDED - I've searched and searched - does anyone know any way to tell the IP of the Google datacenter you hit as you search??? I've tried ping and nslookup, but they give me old IPs that have the old algo. I want to know, if I hit regular G search right now and get the Pigeon algo, what IP am I hitting???