Mark Reinhold, who announced the probable inclusion of closures into JDK 7 at Devoxx '09, has blogged his thoughts on why they're back on the Java agenda. He's looking at a simpler proposal than the ones discussed in Understanding the closures debate.
Incidentally, you can see Mark's talk (as well as the other Devoxx '09 presentations) if you are a subscriber to Parleys.com.