Answer:
This depends on your standard for "intelligence" (artificial or not) and a few other opinions regarding concepts like the metaphysical soul. Whether it is feasible is yet another issue, as the brain might be too complex for us to comprehend within the forseeable future - or the brain might be incapable of fully comprehending itself.
The common defintion, however, is known as the Turing test. According to this test, something is worthy of the term if it convinces humans that it is itself a human. However, some purists object to this definition on the grounds that it is only capable of doing so in specific situations (such as a simple video game) and/or the program logic is obviously too simple to adaquately imitate a brain.
However, the complexity required for a program to be intelligent is difficult or impossible to determine. All programs can ultimately be reduced to several simple constructs such as numerous "while" loops, so this problem is the same as when a hill becomes a mountain. Ultimately all known standards, and even the decision of which standard is best, are subjective - although some arguably more than others.