Google Scholar is here! This new application of Google's popular (nay, essential?) Web indexing and ranking strategy enables the user "to search specifically for scholarly literature, including peer-reviewed papers, theses, books, preprints, abstracts and technical reports from all broad areas of research."
Relevance ranking in Google Scholar incorporates citation frequency data, a la the Institute for Scientific Information's Web of Science product. Also using that citation data, article citations found in Google Scholar incorporate a convenient link to other articles which have cited it.
Importantly, indexing of the literature by Google is not limited to title, abstract, and "subject terms," but includes article full text (where Google has been permitted to access it). This will allow users to do searches on technical details that are all but impossible in traditional indexes, e.g., a search for articles that used a pET28 expression vector, or analyzed their sequence data using PSI-BLAST.
The search engine is in beta form at present, so my advice is not to rely on it exclusively for now -- keep your bookmarks for PubMed! -- but given Google's success in providing access to the general Web, this could be a key milestone in how we search the scientific literature. Read more at http://scholar.google.com/scholar/about.html
I'll be interested to learn of your experiences using Google Scholar over the next several months -- is it working for you? What did you find that you couldn't before? What aren't you finding that you should be able to? Please comment!