Yup, Dr Light uses Amnesium stolen from Superman to scramble the JLA's memoris of their own secret ID's; Green Arrow thinks he’s Ray Palmer; Green Lantern thinks he's Barry Allen, Batman is Oliver Queen, Atom is Hal Jordan, and Flash is Bruce Wayne. Sadly Wonder Woman was out that day or it could have been REAL fun! :)
It also ended with Light having his just-learned knowledge of the JLA's secret ID's being wiped by the Amneisum.