In 2004, about 55% of PhD recipients were non-US citizens, with a strong upward trend. America's finest educational institutions are educating the best students from all over the world, particularly India and China, and sending them home, creating a "brain-drain", weakening our economy and strengthening theirs.
Current immigration policy forces many foreigners studying under student visas to leave the US almost immediately after receiving their degrees. Fewer and fewer employers are willing to apply for the right visas to allow them to stay.
President Obama, I would strongly encourage you to consider a special visa program in which recent graduates in industrially important fields receive H1 visas with their degree, so they could consider staying in the US, improving our economy.