My Duden, Familiennamen has:
KAMINSKI, KAMINSKY:
1. from Polish place-names like Kamie´n, Kamiona, Kamieniec
2. from Polish "kamie´n" (stone, rock), someone living near by am outstanding rock.
For further information try the sister board about surnames:
http://surnames.behindthename.com/surboard.html
Andy ;—)