There are a number of Birdy limited editions, but I'm not sure how many. In addition to the Airstream, I'm aware of these:

Leica Edition (camera company)...



Bianchi Fretta...




Peugeot Edition.. (Also seen in pic above)


(I really love this heavily modified Peugeot Birdy)


....again, there's more special edition Birdy bikes out there, I just don't know where to find a comprehensive "list" of these bikes from over the years.

....BARBIE even had her own Birdy bike!