Siege engines in general don't seem that useful in 2010 compared to the military overhaul. Assuming you can get past the steep curve of getting your military to be able to do anything at all.
I have actually had catapults in 2010 do damage to invaders. They have a minimum range of something like 40-50 tiles. So there's no sticking a catapult up against the drawbridge and shooting at the guys on the other side. I set mine way back into an alcove I carved into the side of the mountain next to the main fort entrance and built a fortified wall well away from the entrance with a sort of cul-de-sac leading into my kill-o-death-gobbo-grinderhallway-o-fun. Invaders would sort of loiter around the entrance as they slowly funneled in to get chopped to bits and I let my catapulter take potshots into the crowd. He mangled a couple. I mean, utterly useless for anything but still fun.
This brings up another interesting question:
Will catapult stones damage any constructions at their point of impact?
Lets assume I have an elevated passageway to my fortress main entrance,
platforms with a z-level of 1, witch lots of traps and spikes atop and connected to other platforms via retractable bridges.
Lets assume during an goblin invasion/ambush I fire with catapults at the goiblins approaching via said passageway...
is there any danger of doing damage to my platformns, traps/spikes or bridges (instead of only hurting/killing goblins)?