This is what I've been able to gather:

There are two implementations of the standard C++ library available on OS X: `libstdc++` and [`libc++`][1].  They are not binary compatible and `libMLi3` requires `libstdc++`.

On 10.8 and earlier `libstdc++` is chosen by default, on 10.9 `libc++` is chosen by default.  To ensure compatibility with `libMLi3`, we need to choose `libstdc++` manually.

To do this, add `-stdlib=libstdc++` to the linking command.


Note: the Makefile supplied with the MathLink examples uses the `c++` command for linking (not `cc` or `ld`).  In this case the `-lstdc++` option can be removed from the linking command.  However if you use `cc` for linking, then it's necessary to specify both of `-stdlib=libstdc++ -lstdc++`.