Just a quick note: all the open-source OCR software out there sucks compared to the commercial alternatives. Honestly and truly, OmniPage or FineReader blows everything FOSS out of the water.
And that’s probably still true, but the situation is getting significantly better.
This particular OCR engine, called Tesseract, was in fact not originally developed at Google! It was developed at Hewlett Packard Laboratories between 1985 and 1995. In 1995 it was one of the top 3 performers at the OCR accuracy contest organized by University of Nevada in Las Vegas. However, shortly thereafter, HP decided to get out of the OCR business and Tesseract has been collecting dust in an HP warehouse ever since. Fortunately some of our esteemed HP colleagues realized a year or two ago that rather than sit on this engine, it would be better for the world if they brought it back to life by open sourcing it, with the help of the Information Science Research Institute at UNLV. UNLV was happy to oblige, but they in turn asked for our help in fixing a few bugs that had crept in since 1995 (ever heard of bit rot?)… We tracked down the most obvious ones and decided a couple of months ago that Tesseract OCR was stable enough to be re-released as open source.
ArsTechnica also has a writeup. This is good news: OCR is one of those applications that not everybody needs, but can be the difference between Linux as a serious option in the workplace and Linux as a neat trick. I know that I have had to boot into Windows just to use Omnipage here at university, much to my dismay.