I've gotten a hello/goodbye siege sequence on 0.44.05:
- Spring year 3: The undead are coming for you. A goblin spearman shows up and immediately disappears.
- Summer year 3: Your enemies are laying siege to your fortress. A goblin spearman shows up and immediately disappears. Both the location and the name of the spearman look like they were the same as in spring.
- Autum year 3: The undead are coming for me. This time it's a force consisting of an eerily familiar goblin spearman handler, a fisherdwarf necromancer, and about 10 undead appear at approximately the same location as in spring and summer.
Unfortunately, the invaders are bugged even worse than the 0.40.X undead invasions usually were. The necro fled more or less immediately (fairly standard), while the undead mill around the handler, who drifts aimlessly with no intention to path into the fortress (like 0.40.X), but the undead are content to fire bolts at targets of opportunity, while not mustering the will to chase anything. The closest entrance tunnel is about 15 tiles away.
It can be noted that an earlier first goblin siege (about 10 goblins) had no problem pathing to the fortress (opposite side of the completely flat 3*3 embark, with a similar entrance tunnel a comparable distance away from their embark entry point).