No, really, pi is wrong: The Tau Manifesto (Tau Day, 2010)

Perfect; to my lisp startup file was just added:

  (defconstant tau #.(* 2 pi))

Regarding adoption, I think it's worth pointing out that these sorts of conventions can and do shift within a generation. I recall quite clearly while growing up the convention for indicating years = the year one [1] was B.C. and A.D. It seems like over the past few years we've definitively decided on B.C.E. and C.E. instead [2].

All it really takes to catch on is adoption by a handful of elementary school textbooks -- and those publishers have adopter much crazier things in the past. As the manifesto points out, this is distinctly pedagogically useful, so it doesn't seem beyond the realm of possibility.

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[1] Correction: Julian/Gregorian years begin with 1 A.D. (I still prefer the AD/BC convention, as the two identifiers have an equal number of characters.)

[2] I'll admit that my perception of prevalence here may be strongly influenced by the fact that Wikipedia has adopted this convention.

I'm just about a math retard, so 99.9% of that went right by me. My only question is this. Pi is supposed to be an infinite number: 3.14... So what would Tau be? Is it also infinite or finite? I didn't see that addressed -- or I somehow missed it in my concentrated skim. TIA.

Their tau is just two times pi.

Both Pi and Tau are irrational (what you call "infinite", http://en.wikipedia.org/wiki/Irrational_number) and trascendental (http://en.wikipedia.org/wiki/Transcendental_number). They are also believed to be normal (http://en.wikipedia.org/wiki/Normal_number), but there is no proof of this.

Tau is an awful symbol in my opinion.

If the people who support double pi as the true symbol they should be writing papers with a definition of double pi and truly proving to the mathematical community that pi is the wrong definition. I personally think pi*D is a perfectly sane way to describe pi and that thinking in 180 degrees is just as easy as in 360 degrees.

Once the math community is convinced good luck with engineers and physicists and then the general public.