Just checked on Chesapeake on my stealther ... I didn't bother checking Trammel, since Chessie is a pretty active shard and I'm sure anything Trammel-side got wiped out. So, my character made his first foray into Felucca!
There were some non-event Ophidian spawns on my way to the keep, and then an enormous glut of event mobs at the exterior. I made my way to the ladder, and checked around inside ... took quite a while, but there were no spawns of event mobs indoors -- just the ones by the entrance top-side.
Even when I was two or more screens off of any monsters in the 'event spawn zone,' I would periodically get revealed, even while standing still. Fortunately, I had a skinning knife with me so I was able to just use Shadowstrikes to keep getting back hidden if I couldn't use Hiding (no Ninjitsu for smoke bombs). I managed to kill a few Recruit-level Ophidians, and got 10x rations.
The Terathran will occasionally spawn in as Avengers, which are actually able to go toe-to-toe with the event spawn. Any mob that dies as a result of the combat between the two monster factions is freely lootable, but
any Ophidian killed by a Terathran will have its corpse despawn as soon as any other mob does the *rummage* action on it.
I killed one Corporal, but didn't get anything special on it, and I loitered around some Avengers to loot other killed Corporals/Majors before they despawned but still just rations. I'm sure the orders and journals are still spawning, but you'll probably need friends to kill the stronger mobs in the numbers you'd have to.
All-in-all, a fun way to spend my afternoon and cut the teeth of my Master Swordsman/Stealther, and I have 10x rations that I wouldn't have otherwise since I started playing after that event technically 'ended.'