Confounded by a bottle of Vitamin Water

I suppose I'll need to apologize in advance for this post...as apparently I'm slow on the uptake.

I could really use some help here.

So I crack open a bottle of Vitamin Water this morning, the latest item of consumption in my rotating cornucopia of breakfast options.

As I'm drinking it, I notice the recycling label...you know, that triangular arrow thing? I always enjoy looking at the triangular arrow recycling logos...it seems to emit an "Oh yeah!" from me every time.

Next to the triangular arrow recycling logo on the bottle of Vitamin Water was a little text referring to said logo, and it stated this:

"30 may be the new 20, but green is definitely the new black. please recycle."

Huh?

Okay...other than being annoyed by the lack of capitalization (which seemed to be a consistent theme throughout the language on the bottle, WTF?), what is this "black" thing all about?

Again, I apologize for this.

Help me out here...I guess I have few points of reference to go by, at least anything that would be obvious to me...what does it mean when it refers to "black" like that? Black in a fashion sense, as in look-at-my-cool-chic-new-spendy-outfit-while-I-walk-around-Manhattan? Is it a Goth thing? ...or black as in a middle schooler "emo" sense? In a beat generation or Velvet Underground sense? What am I missing here? When was black ever it's own unique fad, besides the clothing folks wear to funerals and the day after the world ends when they lose an election?

OMG, I just saw another saying using black in that sense online just now! "Frugality is the new black." it said... Auuuuuuuuuuuuggggggggghhhhhhhhhh!!! I'm being attacked!

I want to believe that I didn't crawl out from under a rock this morning. I recall the fads of the 70s...I recall bell botton jeans...I recall synthesizers and neon being big in the 80s...and I recall purple and teal being big in the 90s...but black? No idea. All I can think of is when the Velvet Underground emerged in the late 60s and all of Lou Reed's schtick, and I believed their black clothing served as a counterpoint to the hippie movement at the time...or perhaps it's always been around, and always been cool? ...and what would you call that, "permachic?" Did I just invent a new word? Am I losing my mind?

So back to the issue at hand. When was black cool? ...and moreover, when was it cool enough to evoke enough status to make its way into pop culture sayings like that, to the effect that it appears on a bottle of Vitamin Water in the year 2009?

Can someone give me a literal explanation of this? Explain it to me like I'm a 2nd grader...and no, I cannot read between the lines.

Please help, it's issues central in the control room today.