Well, there's a story!
In 2002, Disney US came out with the "Disney Bear", a cute teddy bear with a hidden Mickey on his face and Mickeys on his foot-paws (and I think a Mickey mark on his backside too)? There was a story that Mickey hugged him and that transferred the Mickey symbol onto his face, I think, and maybe Tinkerbell brought the bear to life. It did not do well in the states.
The good folks at Tokyo
Disneyland Resort reappropriated the Build-a-Bear-sized bear and eventually named him "Duffy." He's a special bear that Minnie made for Mickey to accompany him on sea voyages. Minnie put a message in a bottle around his neck. While Mickey was asleep on his voyage, he dreamed of Duffy. When Mickey woke up, Duffy magically came to life, and was wearing the same sailor outfit as in Duffy's dream! Now Duffy and Mickey go all around the world and take pictures wherever they go, then share the pictures with people at home.
Duffy became insanely popular in Japan, and they have amazingly high-quality outfits for him over there...he has made the Tokyo Disneyland owners a LOT of money. Obviously US Disney took some interest in that.....
So around October 2010, Disney brought Duffy over to the US, with a similar story to Japan's. He's a special teddy bear that Minnie sewed for Mickey, and Mickey takes him on his voyages. The costumes and even plushies are not generally as high a quality as Japan's, but many items are still cute. When you meet Duffy, he hugs you and generally tries to steal your Duffy plushies if you have any. (In Japan, they say "Duffy Brings Love.")
In the US he has his regular sailor outfit for the meet-and-greet, and then his Halloween outfit and his Christmas outfit (and a lot more outfits you can buy separately, if you get the 17"/Build-a-Bear sized Duffy). In Japan the meet-and-greet Duffy seems to get a unique outfit for every season!
I love him...some people think he's a soulless money-grab but he's adorable and makes me smile, so I don't see how that's bad.