Bandits attacking neutral stalkers more than anyone else, Duty attacking mutants, and so forth.
Monsters and STALKERs alike will now have their own 'schedules' and do things according to the time of day, such as hunting for prey/artifacts during the day, resting in safehouses and patrolling in shifts at night.
According to the game canon, Strelok did in fact destroy the C-Consciousness. Now, here's a few things that we know about the game, and a few promises from the developers:
The game is set to be released in the Autumn of 2009 and carries some pretty hefty system requirements, which should tell you about some of the massive graphical updates / engine work that GSC has been doing with their game. This announcement may be a little late, but ever since GSC has first announced a third title in the S.T.A.L.K.E.R series, the Call of Pripyat, more details have been released.