Taken at GDC at 'Lighting You Up in Battlefield 3' panel...

Hard to say how good it really looks from these Smartphone pics, but damn, if that lit-up smokemoster doesn't look mindboggling...

Fuck yes, night combat! With this lighting, street fighting is going to look so fucking badass.. HEYPEPPEYYEHYPE

do you think those cycles will be active during combat (going around the clock as we play), or that there will be versions of each map, each version set on a certain time of the day/night ? 
 
the former sounds too good to be true, the latter sounds silly, so which one is it ?

" do you think those cycles will be active during combat (going around the clock as we play), or that there will be versions of each map, each version set on a certain time of the day/night ?  the former sounds too good to be true, the latter sounds silly, so which one is it ? "

" It's cool and everything, but how much of the cycle would you actually see during play if it was going on? Not exactly the best game to be showing that stuff off.   ... although. Matches can go on for a while. Imagine if some maps started just before the sun rose or the sun set, that would be awesome. Or if it just randomly picks a time of day each time a match begins. Okay I'm in. "

My thoughts are that this is more of a tech demo to show what the engine can do.. rather than something that will actually be a part of BF3 in any big way. 
 
Though I could very well be completely wrong, I just don't see you being in a level long enough for a day/night cycle to be necessary. 
 
Open-world Battlefield anybody?

Hah! I knew they would show off something like this after the first engine demo video. And you guys said I was crazy.
 
Also, as I mentioned in my initial idea, it's not needed with a shifting day and night cycle. It's just enough with the cycle gradually shifting over the span of a few hours.
Shadows can move quite a bit and interiors become a bit darker and so on. Also fighting in the early morning where the sun is slowly rising would be pretty epic.