Doug Lea of
java.util.concurrent fame maintains the Concurrency JSR-166 Interest Site. One of the interesting links is to Sun bug activity related to JSR166, Concurrency or Collections.
Lea's bug list is very handy for watching for interesting Mustang changes in concurrency or collections as they happen. I only stumbled across the list today—thank Google—, and noticed the nifty Add @see newSetFromMap for Map implementations without Set implementations fix, which got me to look at
java.util.Collections again and check the new methods.