On The Official Google Blog software engineer Paco Galanes
writes:

We’re excited to announce availability of never-before-seen images from the LIFE photo archive. This effort to bring offline images online was inspired by our mission to organize all the world’s information and make it universally accessible and useful. This collection of newly-digitized images includes photos and etchings produced and owned by LIFE dating all the way back to the 1750s.

Only a very small percentage of these images have ever been published. The rest have been sitting in dusty archives in the form of negatives, slides, glass plates, etchings, and prints. We’re digitizing them so that everyone can easily experience these fascinating moments in time. Today about 20 percent of the collection is online; during the next few months, we will be adding the entire LIFE archive – about 10 million photos.

Just add the text “source:life” to your Google Images search to specify images from the archive.

Hat Tip: A Fistful of Euros.