I downloaded the new Eigen 3.1 and noticed that there's now a COPYING.BSD for Intel. After doing some grepping, it seems that Intel's copyright notice only appears in source code related to MKL integration.

I'm using Eigen 3.1 on an ARM platform (iPhone 4) for a closed-source commercial product. Is it safe to assume that I'm not using any Intel-copyrighted code, and therefore don't need to reproduce Intel's copyright notice?

Indeed, the BSD code concerns only the optional MKL integration.

BTW, note that if you modify Eigen's code for your product, the changes have to stay under the LGPL license and they must be freely available to your customers.