Although a few costumes in the upcoming Metal Gear Rising: Revengeance are unlockable, and you can net Gray Fox by way of pre-ordering outside of Europe, another outfit has just been announced: Raiden's Metal Gear Solid 4 armor. The catch? This suit is day one DLC, available for $1.99 on launch day.
Honestly, I'm not a fan of day one DLC in general -- especially when it's something that could have been included in the base game. In this case, I'm just glad it's a skin, and not something that's essential to gameplay, like new abilities, or campaign levels.
As it stands, the only DLC we know of right now is this costume, and some PS3 exclusive VR Missions. Also, both the 360 and PS3 versions will have a handful of VR Missions in the base game, and some skins.
I can live with that.