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Besides the fact that Geek Squad, a company that does IT service and computer repairs, is not a reliable source for info on new malware, Sophos claims it's not aware of any malicious Facebook app using the Christmas Tree name.
Of course, with the message spreading as quickly as it is, it wouldn't surprise us if someone actually created a malicious app bearing that or a similar name. That's the problem with fake warnings: They create confusion and after a while it gets hard to distinguish the fake threats from the real ones.