You should aim for a 3.5 or higher on a 4.0 scale. If you're going for a particularly tough job, maybe 3.8. Less than a 3.5 cuts out a lot of more competitive companies, and less than a 3.0 is pretty much death unless you have a very good reason (this assumes you can get past the HR filters).
What will a 4.0/4.0 get you? Basically nothing, except for some extra bragging rights. My graduating CS semester only had about 5 or 7 people who had a 4.0, but most of us had job offers prior to leaving college. GPA will count for your first or second job out of college, then not matter as much.
Note, I went to a top 10 school for computer science. You may have to scale this somewhat if your school isn't as "rigorous" according to the biases of your interviewers.