Just to reiterate, as part of Daniel's configure cleanup there is now no automatic search for Boost headers in non-standard locations. If you want to build IMP on a Mac with Boost from MacPorts, you need to add /opt/local/include to your search path. (Same deal on Linux if you install stuff in a non-standard location.)
See https://salilab.org/imp/wiki/installation for more detail.
Ben