As consumer search engines become more sophisticasted, rumblings of discontent are occasionally heard complaining that the "invisible Web" remains adamantly hidden. Hidden resources range from corporate records to academic databases. Google is taking a step toward venturing into hidden scholarly resources with Google Scholar, a new beta engine launched today.

Lest euphoria get the better of you, understand the nature of this engine. Google has manasged to gain spidering access to previously hidden resources, but the results often lead to password-protected sites or dumb library catalogs. While Google Scholar is useful in locating academic resources, it leaves them hidden for the most part. However, the engine is still intriguing, and many accessible PDF files come up in the listings. Some scholarly journals maintain browsable back issues: a quick search on the keyword einstein resulted in an article from the American Physical Society's Physical Review.

It's worth noting that this launch follows Yahoo!'s announcement of a co-sponsored library toolbar by just a couple of days. Danny Sullivan's review of Google Scholar is here.