So, as Whispers asked, here are some screens (I took a liberty of editing them, as there are just a lot of funny info). Also, I am not used to forums, so if there are any problems, tell me and I'll fix them.
So, here goes...
I embarked on a sinister desert that borders with good biome. Here we can see some zombies just chilling out in the sun on a field of sand covered in acrid filth. What looks like an aftermath of skeleton party to the upper right is actually teeth of a mule. Last month some werehyena delivered an exceptionally successful punch to some undead mule and all it's teeth flew out in a spectacular explosion %) It was much more hillarious to watch than exploding salt titan.
Also a river full of acrid filth and dorfen\human\elfen\animal blood.
So, here are some details. You can see the *head* and *hand* of Tathadrid, which have all their limbs intact. When werehyenas turn they pick on some ridiculous name which doesn't sound at all dwarfy, so Tathadrid was actually a dorf zombie before he (his parts) died at the claws of hyenas. Oh, and his shambling corpse when it was still 'normal', was decapitated by human swordsman in one swift strike some years ago. As you see, his head is doing well.
Also, a ridiculous undead hand of zombelf Etile... Well, elfs are fragile, zombelfs doubly so. Usually this thing ends up mutilated by undead and comes back to life with all the suffered injuries (which are many).
So, *this* time of month comes and viola: hundreds of werehyenas. I didn't bother making whole lists - announcements span like 9 or 10 pages and it would be just too big an image. You can see that Etile's hand is quite fit (forgot to make a screenshot to show it has no injuries). It was killed shortly after turning by mutilated corpse of an antler or some such animal which was in turn slaughtered by another werehyena.
You can see the aftermath: lots of hyenas on one screen (marked with arrows), pile of mutilated soon-to-be-undead-again-corpses.
Actually, it's quite fun: undeadies chase living creatures, werehyenas chase everything. Sometimes you can see how a crowd of zombies run around the map trying to catch hamster, cow, horse or a giant tick. Elfs are hillarious too.
Here you can see what was an entrance to my fort. The main entrance had two doors airlock style (zombies apparently respect them), to the right there was a door to depot which is, as you can see, demolished. And an entrance to a test labyrinth which serves as a resting place to some twenty undeadies (doors were smashed by berserking werehyenas).
Some zombies usually chill near depot or entrance, so my dorfs can't quite make it outside. Last time I lost five of them, as some restless haunt passed through the door and opened it. Damn ghosts just freak me out. And I actually lost a fortress before when a ghost passed through and opened a door to my undead zoo.
rtg593: After werehyena infection started I actually had a were-ape visiting. I hoped to see what will happen with all the undeads and two were-curses. But it was greeted by a rotting mutilated werehyena corpse and it literally vomited and left map leaving a bloody trail... Had a good laugh then %)
Sting_Auer: I had this happen too. Actually in previous fort I had one dorf woman - Sibrek - who lost her two children and husband to zombies and was left alone with rotting parts of fellow dwarfs in an empty fort. She cleaned it all, broke down to magma and gave birth to a child all by herself %) Her daughter became quite a successful zombie, but was killed shortly and came back as ghost (a child's ghost actually, judging by the picture) and tore her mother's legs off O_O Sibrek then succumbed to insanity, died, came back to life and killed her last baby.