You can't really say that it's come full circle, because it really makes more of a lopsided Q or something. George A. Romero's second Of the Dead film, Dawn of the Dead, was released in Italy (in a slightly different cut, edited by Dario Argento) under the title Zombi. While Romero was making his sequels (Day of the Dead, Land of the Dead, Diary of the Dead) the Italians started a second line of sequels (or a first, since although they were unofficial, they came first). Lucio Fulci directed Zombi 2. Now Romero is a making a currently untitled zombie movie (Island of the Dead is the working title, but may change). This new film has a synopsis that is strangely similar to Zombi 2.
Draw your own conclusions from this.