i' have downloaded boost 1.45.0, installed Python 3.1.3 on my mac.
I have the build Boost with Python succesfully.
For this i had to edit my "project-config.jam" and add "using python : 3.1 : /Library/Frameworks/Python.framework/Versions/3.1;" into it.
At this point all seems to be allright.
Now when i try to use this lib in an xcode project, i have link errors:

Undefined symbols:
    "boost::python::objects::make_nurse_and_patient(_object*, _object*)", referenced from:
        _object* boost::python::with_custodian_and_ward_postcall<0ul, 1ul, boost::python::default_call_policies>::postcall<_object*>(_object* const&, _object*)in libFluxCore.a(Python.o)
    "boost::python::objects::enum_base::enum_base(char const*, _object* ()(void const), void* (*)(_object*), void (*)(_object*, boost::python::converter::rvalue_from_python_stage1_data*), boost::python::type_info, char const*)", referenced from:
        sandbox::BindComponentState()      in libFluxCore.a(Python.o)
        sandbox::BindCallOptions()      in libFluxCore.a(Python.o)
        sandbox::BindFrameRate()      in libFluxCore.a(Python.o)

And lot of more...
Paths and lib are well set in my project.
Does someone have an idea of what can happen ?
Thanks.
I'v finally found this error. buid boost python with 
./bjam toolset=darwin-4.2 architecture=x86 address-model=32 link=static threading=multi runtime-link=static
did the job, as i am on i86 arch.
Linker issue with boost python on Xcode