The Lunar Festival is a time of celebration. The peoples of Azeroth celebrate their triumph of many thousands of years ago, when an alliance of good races (Night Elves, Tauren, and Earthen - a proto-dwarven race) defeated a terrible evil. It is also a time of remembrance for the valor and wisdom of that ancient age.
For this event, Blizzard published the Elunes Blessing Quest which requires that you Summon Omen, defeat him and gain Elune's Blessing. There was also lots of fireworks and elders on hand during the festivities.
If for some reason you missed it here's a real brief video Re-cap:
Elunes Blessing Quest
The cut outs are a little confusing, and of course we don't condone not fighting :) but if you missed Omen in game you can get a pretty good look at him here.
A good look at some fireworks.
Fan Video - Fireworks and Omen
custom music, a look at fireworks, and Omen.
Some Lunar Festival Screen shots: