Possibly it is used with the new high-tech low stretch lines that they are putting in the headsails. Also used with code-zero furlers?
From what I understand, you have to tension these sails that are not attached to the headstay really really hard. You are in effect tensioning the luff of the headsail like it is a headstay.
To do this you need more than 1:1 halyard and a winch. You need 2:1 or 4:1 I guess...