So at first I just checked out the cpp dir. Why not? Well the build breaks in a strange way, something about cannot execute rubygen.mk.
make: execvp: ./rubygen.mk: Permission denied
It turns out that there is a dependency on the specs dir. But autoconf doesn't tell you about it. So you must check out BOTH dirs to a common dir, then build the cpp broker.
svn co http://svn.apache.org/repos/asf/qpid/branches/0.6-release/qpid/cpp cpp
svn co http://svn.apache.org/repos/asf/qpid/branches/0.6-release/qpid/specs specs
That should do it.