I am frequently asked "Is that a yorkie? But it has a tail?!"
I just laugh and tell them that the tail is the yorkie's cuteness meter... and as you can see my Gia's meter is at full capacity.
(That usually shuts them up!)
Truth is, she was the only survivor of her litter, and she almost didn't make it. So they didn't want to put extra stress on her little body by docking her tail. I'm so glad they didn't! I can't imagine her without it, now.