Formalizing a notion of machine Intelligence
Let me give a partial answer from a learning theory perspective.  As your question isn't well specified, this answer won't be either.  In my answer, I'm assuming your question was inspired by your blog post, linked from your profile.

Say that you are thinking about programs that are just functions (so they have to halt, etc.).  You can ask whether certain classes of such functions can appear randomly by, perhaps, looking at the probability a random program (from some distribution that you think is likely) lands in that class or not, with the hope that probability is polynomially large.  I haven't really thought this argument through.

You can also ask whether such a class is efficiently evolvable according to Valiant's model of evolution (also in @Artem's pointer in comments): luckily what is efficiently evolvable is known to be the class learnable by correlational statistical queries; taking "crossover" into account, you get parallel correlational statistical queries. One thing to note is that just because evolvability is characterized, it is still a separate and sometimes difficult task to determine whether a particular class is evolvable (learnable with CSQs) or not.

If you find a class of "programs" that is neither randomly occurring nor evolvable, perhaps you can conclue it has a "creator/programmer," though that conclusion may still take a leap of faith.