The previous example left behind a BUILD subdirectory. Inside this subdirectory are the unpacked source packages that were built. You can build more flavors of globus_common by running gpt-build -srcdir=globus_common-3.5 gcc32 gcc32dbg gcc32dbgpthr. You can see that gpt-build skips over the gcc32 flavor because it was built previously. Reinstalling the same flavor of a package can be done through the -force flag.
The -verbose flag tells gpt-build to print out all of the details of the build. Run the command gpt-build -force -verbose -srcdir=globus_common-3.5 gcc32 to see this. As you can see gpt-build actually builds the globus_common package using the normal ./configure, make, and make install commands. Other packages may have slightly different commands.