USB drives no longer auto-mount on my machine, which hasn't had any settings changes.  I'm able to see the drives with fdisk -l and mount them manually, but I don't ever see a notification or an entry in the places menu for them.  thunar-volman -V reports "thunar-volman 0.8.0 (Xfce 4.10).  This was working yesterday, so I can only assume that one of the updates I ran yesterday is the cause.