Automattic/jetpack — pull request #904 by scotchfield (2014-07-29 15:47:00+00:00)
Title: Replace register_activation_hook with jetpack_activate_module.

As mentioned by blobaugh, to trigger the callback, we need to use
the proper action. Changed the callback function to static, and made
sure we're calling properly on activation.
https://github.com/Automattic/jetpack/issues/882