I built amarok 1.3.7, with libmusicbrainz and libtunepimp already installed, and it appears that I do not have musicbrainz tagging capabilities. Amarok tells me to install musicbrainz.....any suggestions

Have you installed the development (header files) for both packages?

Should be something like libmusicbrainz-dev and libtunepimp-dev and maybe libtunepimp2c2-dev.

A problem that some people have in ubuntu is that libtunepimp was built without support for mp3 files. So if you are using ubuntu you need to download the files from debian unstable.

Good luck