Just a bit of an update on this.
Gigabyte 333 Promo
A full range has now been announced, also added 3x the usual USB power meaning you can run USB hard drives from a single USB header rather than two
Full range to be expected soon, including the GA-P55A-UD6, GA-P55A-UD5, GA-P55A-UD4P, GA-P55A-UD4, GA-P55A-UD3P, GA-P55A-UD3R, GA-P55A-UD3 and GA-P55MA-UD4, just like the existing P55 range.
Still the first manufacturer to offer this too afaik