Seems to be happening in Vancouver, Canada, and all over the world.
and there are some neat pics on this person's blog.
type into your browser www.yarnbombing.com
There is even a book on the subject.
Here is one person's defense of it, when accused of wasting good yarn; should be knitting for the needy etc.....
To all of you puritanical sourpusses who think that the yarn bombers should be making sweaters for the needy...
Do you have some extra space in your house/apartment/condo? You should invite homeless people to live with you. You have room. Why are you wasting all that room on yourself? How selfish.
Do you spend your free time watching TV? You should be spending that time volunteering at homeless shelters and food banks. How dare you spend your free time on mindless entertainment when there are so many people out there suffering?
Nobody's allowed to have any fun until the world is perfect, huh?