There are some extremely intelligent people in business (by which I mean high IQ, not just wise or experienced), but you tend to find them in the corners of the business landscape [...] Steve Ballmer - for instance - might deafen you, but he would not dazzle you.

No comment on his ability to dazzle, but Ballmer certainly does have a high IQ:

In high school, Ballmer scored a 1600 on his SATs and was a National Merit Scholar.

As a college sophomore, Ballmer finished in the top 100 in the prestigious Putnam national math competition, and ended up graduating magna cum laude in applied math and economics.

http://www.thecrimson.com/article/2002/6/4/personable-ballmer-leads-college-extracurriculars-microsoft/