There is no doubt that people all over have been hanging things on fences for some time now.
Examples this blogger has seen with his own eyes include boots (NZ), bikes (NZ) and underpants (West Australia).
But most of these are about random fun, not about public protest.
Down here in the deep south of West Australia our sock fence has deep and heart felt meaning.
Sure, it looks good. Sure it's fun. But we're angry.
We want a vacant site replenished, or returned to the community.
Anyway, check the others out:
locks and lovers
locks and lover
weird stuff in NZ