I remember seeing some penguins on boot on airline entertainment systems. It was amusing. It's definitely something they could configure off, but didn't.

I remember being excited about more than one penguin as well. They even got little suns on their bellies when I booted on a Sparc64 machine!

I definitely remember Tux showing up in boot, but I don't remember when it started appearing or when it disappeared. (when/what kernel version).

It appeared on the CentOS 7 install I made earlier this year.

Fortunately, only about 8 or 9 show. 96 would fill up the screen.

(I had trouble on some new hardware with the usual automated install, so I watched what was happening.)

AFAIK, it's still there if/when using framebuffer mode.

It can be compiled out of the kernel (that's what most distributions do these days), or disabled with a boot option. Try:

  $ zgrep CONFIG_MODULE_SIG_SHA224 /proc/config.gz
  $ grep logo /proc/cmdline