One was written yes, but it was not made public. Reason being is that every gp2x has 42 bad blocks due to the way GPH manufacture the GP2X, and secondly, you need to write to every block to see if the status has changed from "good block" to "bad block".
Bad blocks on the nand don't make a difference anyway - if a block goes from good to bad, it'll just be marked as such and reallocated - the end user won't notice any difference.