(In agreement, just to express it another way): Patents on implementations can and do effectively limit idea reuse. E.g. if the idea is "a web 2.0 flower box"

(In agreement, just to express it another way): Patents on implementations can and do effectively limit idea reuse. E.g. if the idea is "a web 2.0 flower box" making a second implementation is fine. If the idea is a "web 2.0 flower box using this specific patented method of procedural generation" then you won't be able to recreate the same product again - at least not without moving to Europe where there are no software patents :)