Writing an extension - dyld: ...Symbol not found

I'm writing an extension called "V8PHP". It's similar to the V8JS extension,
but the implementation is quite different.

I'm having trouble linking the v8 library to my extension. When I run a PHP
script via CLI I get:

dyld: lazy symbol binding failed: Symbol not found: __ZN2v86String3NewEPKci
Referenced from: /phpdev/lib/php/extensions/debug-zts-20090626/v8php.so
Expected in: flat namespace

dyld: Symbol not found: __ZN2v86String3NewEPKci
Referenced from: /phpdev/lib/php/extensions/debug-zts-20090626/v8php.so
Expected in: flat namespace

Trace/BPT trap

I have PHP installed in /phpdev/ (--prefix=/phpdev). v8 was compiled with
gyp using the following commands:

cd /v8/
make dependencies
make native

And this outputted these files to /v8/out/native/:

libpreparser_lib.a
libv8_base.a
libv8_nosnapshot.a
libv8_snapshot.a
obj/
obj.target/

And the obj.target directory has a bunch of .a files in
obj.target/v8_base/src/.

I created a soft link from /v8/include/v8.h to /phpdev/include/v8.h,
/v8/include/v8stdint.h to /phpdev/include/v8stdint.h, and
/v8/out/native/libv8_base.a to /phpdev/lib/libv8.a.

My config.m4 file looks like this:

PHP_ARG_ENABLE(v8php,
[V8PHP],
[--enable-v8php Include V8 JavaScript Engine])

if test $PHP_V8PHP != "no"; then
SEARCH_PATH="$prefix /usr/local /usr"
SEARCH_FOR="/include/v8.h"

if test -r $PHP_V8PHP/$SEARCH_FOR; then
    V8_DIR=$PHP_V8PHP
else
    AC_MSG_CHECKING([for V8 files in default path])
    for i in $SEARCH_PATH ; do
        if test -r $i/$SEARCH_FOR; then
            V8_DIR=$i
            AC_MSG_RESULT(found in $i)
        fi
    done
fi

if test -z "$V8_DIR"; then
    AC_MSG_RESULT([not found])
    AC_MSG_ERROR([Unable to locate V8])
fi

PHP_ADD_INCLUDE($V8_DIR/include)
PHP_ADD_LIBRARY_WITH_PATH(v8, $V8_DIR/$PHP_LIBDIR, V8PHP_SHARED_LIBADD)
PHP_SUBST(V8PHP_SHARED_LIBADD)
PHP_REQUIRE_CXX()
PHP_NEW_EXTENSION(v8php, v8php.cc v8_class.cc, $ext_shared)

fi

It seems like libv8.a is trying to link to something else... but I'm not
sure. My extension compiled fine.

I'm on Mac OS X 10.6.x.

Anyone know what the problem could be?

Luke