There is an open-source OCR enginge called Tesseract which seems relatively well accepted and documented. Might be a good place to start for someone interested in playing with text recognition in maemo..

It's been used in various licence plate recognition experiments:
http://www.youtube.com/watch?v=9vzR_H-jjHk
http://www.youtube.com/watch?v=BTpIpn7w1lg