Runeforging appears to be the Death Knights answer to rogue poisons. They are basically weapon enchants that have no time limit and can only be changed at a runeforge. Here is a list as of the current beta of the available forges:

Rune of Cinderglacier
Affixes your rune weapon with a rune that has a chance to increase your Frost and Shadow spell damage by 10% for 15 sec. Modifying your rune weapon requires a Rune Forge in Ebon Hold.
5 sec cast

Rune of Frostfever
Affixes your rune weapon with a rune that has a chance to inflict a disease that causes Frost damage and lowers attack power by 10% for 20 sec. Modifying your rune weapon requires a Rune Forge in Ebon Hold.
5 sec cast

Rune of Lichbane
Affixes your rune weapon with a rune that has a chance to strike undead for extra Fire damage and stun them for 5 sec. Modifying your rune weapon requires a Rune Forge in Ebon Hold.
5 sec cast

Rune of Spellbreaking
Affixes your two-handed rune weapon with a rune that deflects 5% of all spell damage. Modifying your rune weapon requires a Rune Forge in Ebon Hold.
5 sec cast

Rune of Swordbreaking
Affixes your two-handed rune weapon with a rune that increases Parry chance by 3%. Modifying your rune weapon requires a Rune Forge in Ebon Hold.
5 sec cast

Rune of the Fallen Crusader
Affixes your rune weapon with a rune that has a chance to heal you for 3% and increase total Strength by 30% for 15 sec. Modifying your rune weapon requires a Rune Forge in Ebon Hold.
5 sec cast

A blue post in the beta forums posted some clarifications on 2h vs. 1h forges:

We plan to add, at the very least, one-handed versions of the two-handed enchants.

Having 5% parry on each weapon would be a little crazy, but we could offer 2.5 or 3% on a one-handed weapon. Ideally we’ll add some more as well.

The Runeforge

The Interface

Here is a squirrely little gnome showing it in action:

We have an ongoing discussion in the forums, feel free to join in!