.co made a deal with google to rank as a non-location based domain, just like .com/net/org - that's why they were supposed to be great - they gave you another shot at a location-generic domain for some tough terms.
It's a lot more like .info in practice though
The biggest problem with .co domains may be just that since they haven't been around as long, no one's really done too much work with them yet.
I predict eventually you will see them as much as .info - not much, but ocasionally you will come across one.