From Paul Vragel:

Never a dull moment.  As we were leaving the Velodrome in Northbrook Ken
noticed something odd looking about one of the chainstays on my bike.  On
closer inspection, it's cracked more than 60% of the way around.

I had done a detailed frame cleaning 2 weeks ago and saw no damage in this
area and have never fallen or dumped the bike.  The crack is right in the
middle of the chain stay, exactly where the physics would say you have
maximum bending which could cause a fatigue crack like this.  OK, enough
analysis.

Ken and Donna provided some duct tape for the proverbial jury rig, just to
provide a minimal way of preventing sudden failure (it got worse
anyway...).  Trish offered to trade bikes to take some of the stress off. 
We traded, and rode more slowly - then when we got to the end of Happ
Road, Trish stopped and couldn't get her shoes unclipped.  I rode up just
as this was happening and was able to catch her before she fell.   We
traded back, and I rode the bike very slowly back home.  I took the bike
over to Turin - the frame should be covered by the warranty, and they'll
be in contact with the Specialized rep early next week.