Wow, they're picking a dual national to head an agency charged with promoting investment by US companies in developing countries. I'm not sure what you should be more worried about: that she holds a British Passport or that there's an agency of the US government that has the task of promoting outsourcing.
Now, on the other hand, I've worked with the former head of Congressional Liaison for CIA and he had dual US/UK citizenship too.
I'm quite surprised that the requirement for the president to have been born in the US (with a few caveats) has not been changed. I understand why it was originally introduced but we live in a different world.
I know change has been mooted before to deal with specific possible candidates - Kissinger and the Gubernator are two that spring to mind.