[gpcz]

As you said, the author was probably mixing up ghettos (which are by definition involuntary) with the concept of an ethnic enclave ( http://en.wikipedia.org/wiki/Ethnic_enclave ). It's easy to do because many ethnic enclaves were historically ghettos, but the involuntary factor was removed and the region developed a unique culture that remains.

[lrem]

To make it even more confusing, I've heard that at least some ghettos in German-occupied Poland were ethnic enclaves before the war. OTOH, never cared to find actual sources to support/disprove this claim.