The talents and abilities for Death Knights changed with Patch 3.1. To keep up to date many of the pages of our Death Knight Guide have been refreshed. You can find all the changes at the following pages:
Blood is a standard talent build for both leveling and end game PvE content. While it does not put out the full run damage numbers that an Unholy spec does, it is able to keep going and going and going. Think of the Energizer Bunny crossed with a rabid pit bull ripping people apart and you are not far off. Blood has many talents that boost a Death Knight's self healing ability, grants healing to others, and boosts damage.
You can find all the updates here:
You can also comment on the updates in the forums here.