try tesseract,
checkout this article
http://www.itwizard.ro/interfacing-cc-libraries-via-jni-example-tesseract-163.html
and this example
http://code.google.com/p/mezzofanti/
Edit:
some more facts
- tesseract is one of the best open source OCR used by google
- there is training data available for many languages
- mezzofanti is an android app that uses tesseract
- beware: OCR does use a lot of CPU power. trying to OCR a A4 page with your T-Mob G1 will take a lot of time and the result may not impress you ;-)