A decision from the Central District of California in August in the Ultramercial v Hulucase showcases a concern that we expressed about how cursory reliance on a claim being unpatentable because it is "abstract" can lead to unfortunate results. An amicus brief we filed in the Bilski case warned of the problems that could result if the Court applied the term "abstract" without providing a clear indication of the sense in which that term was being used. See amicus brief of On Time Systems (also can be found in the Supreme Court Proceedings tab of this blog).
A claim that is just a vague expression of a concept may be considered "abstract" and therefore correctly be held unpatentable. On the other hand, there are many claims that clearly are eligible for patent protection even though they deal with abstractions. For instance, any use of a sensor deals with something that is abstract - the example we gave in the brief was that a signal produced by a wind sensor is an abstraction of the force of air molecules striking the sensor. Just because a claim is based on a signal from a wind sensor does not mean that it is abstract and therefore unpatentable.
Unfortunately, the apparent deadlock among the Justices that led to the Bilski decision turning on a cursory statement that Bilski's claims were abstract, rather than either a detailed discussion of what that meant or a different ground (e.g., one of the issues presented as the ones that were before the Court) has encouraged other courts to likewise look to a quick "abstract" route to invalidating patents.