Why is everyone treating this as something new?!?!

you run code on your machine, you have to trust it.

Heck, i don't trust even stuff i download from the app store! and I still limit the talk of my wii with nintendo servers on my router.

the chrome extensions just add a little insult because it 'seems' official or something. Much better the grease monkey way, full of warnings so the user remembers that he has to think for himself.