[jandrewrogers]

That is not quite correct. You cannot patent something that precludes the use of a mathematical concept but you can patent a method for applying a mathematical concept. For example, you cannot patent "sorting" but you can patent a "bubble sort algorithm" because the latter is one of an infinite number of methods in which the mathematical concept of sorting can be implemented. The RSA patent did not prevent people from using public key cryptography (either in theory or in practice), only one particular algorithm for implementing such a concept.

Algorithm patents are allowed in most countries, contrary to popular belief; when most people talk about "software patents" they are actually talking about business process patents which rarely exist outside the US. Actual algorithms are recognized as a direct abstraction of electronic circuit designs and electronic circuit designs are widely recognized as patentable subject matter.

(Any consistent application of an "algorithms are mathematics" argument would exclude all currently patentable subject matter, for better or worse. I do not have a strong opinion one way or the other but it is worth pointing out because this fact is lost in many discussions of patents.)

[brlewis]

Benson's patent was for a particular algorithm, not an abstract concept, yet it was found invalid: http://en.wikipedia.org/wiki/Gottschalk_v._Benson

The RSA patent didn't make it through the patent system by claiming a particular algorithm; it made it through by including the hardware: http://en.wikipedia.org/wiki/RSA_(algorithm)

See also http://en.wikipedia.org/wiki/Freeman-Walter-Abele_Test