From his wife's Livejournal:

On Wednesday afternoon, June 1, 2011, Joel had a respiratory depression that caused a heart attack, anoxic brain damage and major organ failure. Despite the very best efforts of the paramedics and the team at Hennepin County Medical Center, Joel was pronounced brain dead at around 5:37pm Thursday June 2nd, In accordance with his wishes, he shared the gift of life through organ and tissue donation.

He is survived by his daughters, Judith Eleanor and Rachel Hannah, and his wife, Felicia Herman. Today, June 3rd would have been his 32nd wedding anniversary.

Our condolences to the family. I remember reading Joel's books in high school and enjoying the heck out of them.