I will be adding to this as I gather information but I wanted to get something up on this page before these things hit the market.
On the heels of the BCIA warning about fake Freehand carriers, I found a co-op group on Facebook who KNOWINGLY bought fake Ergos. Beware of buying an Ergo used. These are really high quality knockoffs. They are sold using the Ergo name brand, they have an Ergo box, Ergo tags and zippers and an Ergo DVD. However Ergo themselves has verified that they are fake. There are differences and I have photos to compare them. You can also read more here from the wonderful Jillian of PaxBaby.
For now my recommendation is buy only from Ergo's list of authorized retailers. If you purchased an Ergo from Babysteals, they are real. If you got one from Amazon, probably real. Don't panic if you bought one used and can't verify it's authenticity. It's probably fine. But for now if you are in the market for an Ergo, stick to new ones from known retailers.
Best wishes and safe babywearing!