First I was persuaded about the oil speculation topic, now I find myself agreeing with Mankiw about opening our immigration laws to allow more higher education seekers into our country.
I've spoken on this topic before, and have been advocating this for some time myself. Nothing is more important in terms of long run growth than education and the knowledge and positive network effects and externalities that can flow from that.
I would actually go farther. I understand the need to limit immigration to some degree, but in my opinion, foreigners that want to come to our country to pursue high degrees (Masters or above) should be given an automatic and speedy path to citizenship (providing the individual agrees to stay in the United States X number of years), in addition to the instant access to a green card.