The Hearthstone team has unveiled a new event for players called the Quest for Packs Sweepstakes. From February 1st through February 14th, completing a single daily quest per day offers players an entry into a sweepstakes where the grand prize winner will receive 3,000 card packs to open, the Lich King's Helm (ZOMG!) and a Hearthstone Apparel Gift Pack.
Other prizes include 1,000 players taking home a Mammoth Card Bundle (10 packs from each expansion released during the Year of the Mammoth) and 50,000 players set to win the Mammoth Pack of three card packs from each expansion.
A new bundle is being added to the Shop in honor of the Year of the Mammoth. It contains 10 card packs from each expansion. While these can be won for participating in the Sweepstakes, it can also be purchased (1 per account) starting with the 10.2 update.
You can check out the full details on the Hearthstone site.