Actually, this feature is in the testing stage at the moment, but you can try it out for yourself. Just upload any JPEG, GIF, or PNG image that's 10MB or less. The smaller the file, the faster Google will convert it to text and turn it into a new Docs document. (A 2MB file will take about 40 seconds, for example.)
The folks at Digital Inspiration did some testing of Google Docs OCR; here's an example of the results:
Still, the price is right, and this could come in handy for anyone who owns a scanner but no OCR software.
What do you think? Is this something you would use? Personally, I'd love to see support for PDF and TIF files, but even so I'm hoping Google makes this a permanent part of Docs' feature set.