My experience has been very satisfactory when I've tilled the pond muck into existing topsoil. Our parent soil in this area is low in fertility; any addition of organic matter has helped grow stuff, whether it be vegetables, trees, or flowers.
Your idea of spreading and disking it will likely work very well for you. I tried a small patch of muck without incorporating it into soil. While still saturated, it was monsterably (I'm not sure that's a word. Help me out, @Teeh Jaeh) sticky. It hardened into clods that would grow nothing.
We had a thread on here a year or two ago that discussed lots of this. In order to sell it, a person would probably have to dry it out for a lengthy period of time, as in 6 months, a year, 2 years, to reduce its weight for hauling purposes.
Unless the deposits on your pond bottom are simply eroded silt, sand, or clay, I think you will achieve good results.
YMMV
