The JDK 8 Project has just been created. If you contributed at least one changeset to JDK 7 then you've automatically been subscribed to the jdk8-dev mailing list.
If you didn't contribute to JDK 7 you're still welcome to subscribe to the JDK 8 list, but you'll have to do so yourself. Either way you can subscribe, unsubscribe, and adjust your subscription options here: http://mail.openjdk.java.net/mailman/listinfo/jdk8-dev . - Mark
