Palace swoop for Birmingham's Danns
Danns has signed a three-and-a-half-year contract with the Eagles and the eventual fee could rise to £850,000 based on add-ons.
Birmingham boss Alex McLeish had made it clear that Danns and central defender Martin Taylor were surplus to requirements.
McLeish said: "We would like to bring other players in and that's going to hold certain players back.
"Neil is a guy who, at this stage of his career, should be getting first-team football and we wish him all the best."