[jasiek]

I guess that overriding the behavior of any built-in classes in Ruby is not a great idea, as most gems rely on that unmodified behavior.

[DanielRibeiro]

As a gem creator, is is terrible.

As a application creator, is is only bad when/if you open source part of it. Otherwise, you can always run the gems' tests against the compillation of your env.

[jaylevitt]

There's talk of "traits" for Ruby 2.0 that will let you scope your monkeypatching.