User blog comment:Juicestain09/Red Dead Redemption DLC Trophies/@comment-Achievements revealed!/@comment-175316-20100530211942

I would think given the way the new achievements are handled on the 360 for other games that they probably won't be viewable until it's patched for the DLC, which on most other games I've got doesn't seem to happen until very close to the release of the DLC.