i do the work as following:
0.install bjam
1. down boost_1_40_0
2. untar to disk root directory
3. ./bootstrap.sh ---with-library=thread
4. configure user-config.jam as following:
using darwin : 4.2.1~iphone
   :
/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/g++
   : <striper>
   : <architecture>arm <target-os>iphone <macosx-version>iphone-2.1
   ;
using darwin : 4.2.1~iphonesim
   :
/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/g++
   : <striper>
   : <architecture>x86 <target-os>iphone <macosx-version>iphonesim-2.1
   ;
5. command at console:
bjam --prefix=/usrLibs/boostiPhoneDev toolset=darwin architecture=arm target-os=iphone macosx-version=iphone-2.1 define=_LITTLE_ENDIAN link=static install
...
...
....
..
Any setting missing ? how to deal with it?

In file included from ./boost/config.hpp:40,
from ./boost/thread/detail/config.hpp:10,
from libs/thread/src/pthread/thread.cpp:8:
./boost/config/select_stdlib_config.hpp:17:19: error: cstddef: No such file or directory
In file included from ./boost/config/select_stdlib_config.hpp:33,
from ./boost/config.hpp:40,
from ./boost/thread/detail/config.hpp:10,
from libs/thread/src/pthread/thread.cpp:8:
./boost/config/no_tr1/utility.hpp:21:21: error: utility: No such file or directory
In file included from ./boost/thread/pthread/thread_data.hpp:9,
from ./boost/thread/thread.hpp:17,
from libs/thread/src/pthread/thread.cpp:10:
./boost/thread/exceptions.hpp:19:18: error: string: No such file or directory
./boost/thread/exceptions.hpp:20:21: error: stdexcept: No such file or directory
In file included from ./boost/smart_ptr/shared_ptr.hpp:27,
from ./boost/shared_ptr.hpp:17,
from ./boost/thread/pthread/thread_data.hpp:10,
from ./boost/thread/thread.hpp:17,