The US Supreme Court was asked to review the infamous Bilski business methods patent decision handed down en banc in October by the Court of Appeals for the Federal Circuit limiting patents to things that "transform an article to a different state or thing" or are "tied to a particular machine."

The decision, which rocked the patent world, has serious implications for software patents. That's why companies like Microsoft, Red Hat and IBM filed friend-of-the-court briefs.

It now remains to be seen whether the Supremes will deign to hear the case. Their decision could come before the end of the current term in June.

The appeals court, which expected a Supreme Court review, consciously sidestepped the issue of software patents, leaving it, it said, to future cases.

Unresolved, for instance, is whether a computer, the point on which many software patents rest, makes the cut as the machine. The Patent and Trademark Office these days thinks general-purpose computers don't but it has reportedly been inconsistent in applying the Bilski principle.

The October ruling, called a "throwback to the 19th century when the economy was manufacturing-based," overturned the 1998 State Street Bank decision that opened the door to business method patents. It said the test for patentability was simply a "useful, concrete and tangible result."