Jo Piazza's Sunday column, "Full Disclosure," debuted yesterday in the Daily News.

Piazza, who got her big start as a stringer for Rush & Molloy, marks year No. 3 with New York's hometown paper. And while she's working her own gossip sources, she also finds herself in the same circumstances as Ben Widdicombe used to, when he had a weekend-only column: By the time Sunday roles around, most of the decent scoops have been picked up. And speaking from experience, it takes a trustworthy source to keep her mouth quiet and not spill to the competition — even at the same rag.

And what not-good-enough-for-the-weekdays items did we have to look forward to? A Fashion Week party face off between Marc Jacobs and Diddy, with nice plugs for Cadillac and Ciroc vodka (which Diddy endorses). Oh, and the first eyewitness report of Jacobs, Jason Preston, and porn star Erik Rhodes making their threeway relationship public.

Elsewhere, Mary-Kate Olsen, despite her day-after partying, still feels terrible about the death of Heath Ledger, who she'd been dating "casually." And an obvious blind-item.

We have to ask: Which hard-partying and over-sexed young starlet's signature move is leaving behind her panties at her paramours' houses? Tail-chasers all over L.A. have a collection of lacy things to remember her by.