Hadn't seen that, only a pay for app (and I'm cheap :))! Anyway, Focus is tailored perfectly for me, hope some other people can find use out of it too.
Edit: Clarification (I'm sorry I can't reply to your comment, it won't let me), I meant I had only seen a pay for app and not this one.
Edit 2: (reply to comment also) also doesn't appear to have exceptions, maybe I'm wrong.
Self Control does the same thing and it's been open source on Github since March 2009.