.Co is identical to .Com as seen by Google.
I asked the question to Google when I bought my first .Co because there was no option to GEO target it, it was grayed out.
They replied with something along the lines of "Yes it has been opened up to everyone and yes it ranks the same, the option will be there for GEO targeting soon, we are working on it..."
Something similar to that anyway.
Sorry, I deleted the message so can't quote it.