Can you imagine...

...illustrating something that is as famous as the twitter bird and selling it on istock and then finding it on something like twitter?

I have found the original twitter bird illustration! http://www.istockphoto.com/stock-illustration-3412146-eco-sing-song.php after a hint from @aigacharlotte. Apparently Simon Oxley (a British designer living in Japan...he actually went to Japan to find a wife - which he did) also created the istockphoto character (and he says the logo but I'm not sold on that).

You can catch his interview here: http://reubenmiller.typepad.com/my_weblog/2007/11/exclusive-inter.html

By the way, since it's actually still a royalty-free image, you can have the twitter bird too.