From Rubi at Anet (link to forum post):
Due to an unexpected bug, the Community Goals tracker for Champion Rush is not working properly. We want the community to enjoy the rewards it would have collectively earned, so we are going to complete the goal now and award all five Community Goal tier rewards to players who participate once the event ends. Champion Rush will still continue until August 27 as planned, and you will continue receiving individual rewards when you participate.
Here's the list of all the Community Goal tier rewards:
Tier 1:
3 Celebration Boosters, 5 Guild Gold from Kills Banners, 5 Tier 1 Embroidered Coin Purses
Tier 2:
3 Celebration Boosters, 5 Guild Gathering and Swiftness Banners, 10 Pact Scout’s Mapping Materials, 5 Tier 2 Embroidered Coin Purses
Tier 3:
3 Celebration Boosters, 5 Guild Karma and Experience Banners, 5 Trays of Omnomberry Bars, 5 Tier 3 Embroidered Coin Purses
Tier 4:
3 Celebration Boosters, 5 Guild Gold and Magic Find Banners, 10 Bonus Boxes of Goods, 5 Tier 4 Embroidered Coin Purses
Tier 5:
3 Celebration Boosters, 5 Guild Heroes Banners, 5 Tier 5 Embroidered Coin Purses, Endless Champion Angry Chest Tonic
There's lots of free stuff coming your way, so keep participating and bashing those so-called champions!!