You may know that the interactive shell of python uses Gnu-libreadline (in GPL) to implement the history retrieving feature. However, does this impact your own python program or application with python interpreter embedded in?
I did a little study on the python interpreter, libraries and built-in modules on linux (which were built with libreadline), looks like there is only one extension module links to libreadline, /usr/lib/python2.5/lib-dynload/readline.so. And this module would only be loaded by the interactive python shell. When I launch an ordinary python script directly, or embed python interpreter to a C/C++ application, this module would not be loaded, unless the script imports the readline module explicitly. (P.S., I used pmap(1) to verify if libreadline.so is loaded in runtime.)
I think only the readline ext module is under GPL term, and it should be safe to build python with libreadline.