Well, all sufficiently strong programming languages are equivalent in the Turing sense, and Turing machines are equivalent to lambda calculus in computational power.
That said, lambda calculus is rather different from standard procedural programming. The closest thing to it in the "real world" would be functional languages such as Scheme, ML and Haskell.
What makes functions special? I think the article answered that: with very simple ingredients, namely recursive functions that take only 1 argument, you can essentially write any program that you could write with full-fledged Ruby (or any other Turing-complete programming language).
That said, lambda calculus is rather different from standard procedural programming. The closest thing to it in the "real world" would be functional languages such as Scheme, ML and Haskell.
What makes functions special? I think the article answered that: with very simple ingredients, namely recursive functions that take only 1 argument, you can essentially write any program that you could write with full-fledged Ruby (or any other Turing-complete programming language).