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Regardless of whether it was permanent or temporary, GoDaddy's switch was a signal that the American and international web is moving away from the now-crowded .COM standard. We're anxious to see what GoDaddy learned in its test, but if you look at the registrar's Twitter conversations, you'll see that quite a few people jumped on the bandwagon and embraced .CO domain names with their new registrations.
The move away from .COM is inevitable, because there simply aren't that many .COM domains left. You'd be hard-pressed to find your first choice without going for something else; it's just a question of which extension will be the most popular successor. Right now .CO is a promising contender.