You can read the latest Hellgate: London preview at 1Up. Here's some of it:
By varying these optional tasks and interactions with NPCs, the team at
Flagship is looking to create a more immersive world. "[A change in the
world] might be daily, it might be weekly, it might be every seven
hours or something -- in single-player we run it off your clock, and in
multiplayer we'll run it off a master clock. So you might go to the
shopkeeper and he says, 'Oh yeah, I'm looking for these batteries.' And
the next day you might come in and he says, "The Templar are planning
this big raid, and they're looking to get their hands on as many
Scorchers [one of the weapon types] as possible. So for every Scorcher
you bring me, I'm running low on cash but I'll mod a weapon for you.
I'll add a mod slot to a weapon. So now you're like, 'I've gotta keep
my eyes open for that. And it's not like 'Go here and kill these wolves
and I'll give you a pair of boots.' It's just like, 'Hey if you happen
to come across any of these, and you get this many of them, I've got a
special thing I'll give you for that."
So he's saying that there are events that run in real time, from
your system clock. That could be a good way to add hours to the playing
time, or stupid because you have to wait a week for something to change.