WotC_Logan said:Honestly, this is what we have DMs for.
Good rules of thumb are "has it been 5 minutes" and "did we break out of initiative?"
Grymar said:Very cool, but the new argument will be when does one encounter end and another starts.
This was stated by the designers? I missed it. Things certainly seem to be moving in that direction, but I don't remember anyone actually saying that this is how it's going to be done in 4E.Chuangel said:What glad news that buffs just last until the end of the encounter, and that's it.
Li Shenron said:Some questions will also certainly be raised when someone will try to run an army scene and all buffs will last two hours.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.