If you hadn’t noticed on Twitter and Facebook today is World AIDS Day and Foursquare is offering up a new badge for the occasion. Just use the hashtag #turnRed in your checkin or in a shout and you’ll unlock the (RED) badge.
Additionally you can checkout which of your friends also have unlocked the (RED) badge by going to your badges page and clicking on the badge. This actually works for all your badges.
You can also follow along on this cool map to see all the (RED) Foursquare activity.
As a bonus (RED) effort, I’ll point out that @Starbucks is giving 5 cents to fight AIDS for every view the new Killers video get.