There's a new link to Google Scholar in the list of services from the "more" box. Google's search engines for scholarly papers was available on the homepage only if you visited Google from your school.
Google Scholar includes a big list of scientific publications and some of them aren't available in Google's main index. "Google Scholar covers peer-reviewed papers, theses, books, abstracts, and other scholarly literature from all broad areas of research. You'll find works from a wide variety of academic publishers and professional societies, as well as scholarly articles available across the web."