I have received numerous questions in light of various court decisions, most recently Alice Corp. v. CLS Bank, about whether software patents are still viable. The answer is "yes."
The court in Alice Corp. did find the patent at issue too abstract to qualify as patentable subject matter under the law, but the U.S. Supreme Court did not vanquish software patents with the stroke of a judicial pen. The court followed precedent it established in prior patent cases, and simply pointed out that the invention one is seeking to patent has to be patentable on its own merits. In other words, an otherwise unpatentable method cannot be rendered patentable merely because it is described as computer software.
The court did not draw a firm line as to which inventions are eligible for patent coverage on their merits and which are not. Inventions are too varied in scope and characteristics for any court to provide a workable, concrete rule that covers all situations.
As with other inventions, software inventions will have to be evaluated on their own merits, as inventions. If the method carried out by the software is otherwise unpatentable, then describing the invention in terms of computer software won't rescue it in the patent office.