This is based on legowxelab2z8's InterruptThat (GPLv3). I just made it work post-Drop #5.
This addon shows cooldown timers for group member's interrupts. Group members and interrupt icons are added as spells are cast. Players in your party that have the addon will have a green name bar indicating that the information is more reliable. Cooldowns for other players without the addon will fall back to monitoring the combat log for spell casts and will still have the old limitations making the data less reliable.
Click and Drag player names to move the window.
Right click on a spell to temporarily remove it from tracking (will show up again next time it is cast)