In case you forgot, Google was involved in a little spat with Oracle earlier this year, in which a jury decided that Oracle's patents were not infringed by Google, and a judge came to the conclusion that Oracle's assertion regarding API copyright infringement was untenable.
Judge Alsup's reasoning in denying Oracle's infringement claim was, to anyone with a technical background, quite reasonable. Oracle had claimed that while the amount of line-for-line literal infringement Google committed against the 37 infringed Java APIs through its Dalvik virtual machine was minimal (read: 97% of Google's code was original), the fact that Google had copied created its functional equivalent constituted copyright infringement. Oracle's assertion there resembles a patent argument far more than it does a copyright one.
Oracle has also dropped its patent claims on appeal, and is instead focusing only on the API copyright issue. So, what exactly is the issue? Whether an API be copyrighted in the fashion Oracle alleges; in which two APIs are written in the same language, and are functionally though not literally identical. Which is to say, they carry out the same set of commands, even if they don't look the same. Oracle goes beyond even this, to say that the infringement of the copyrighted API does not even require complete infringement of the functionality, merely part of it.
The issue of API copyrightability in this fashion is indeed novel to the 9th Circuit Court of Appeals. The problem with Oracle's assertion is rather fundamental: a copyright, by definition, is meant to protect form, not function. Function is protected by a patent. Oracle's argument, though, will likely be something along the lines of Google copying the melody to Oracle's song (melodies are indeed copyrightable), then altering the key, switching the bass guitar for an upright, and changing the lyrics.
The question, though, is if an API's unique combination of commands - the end result of which is utilitarian in nature - is the same as the unique melody of a song, which serves no functional purpose. From a common sense standpoint, obviously not - Oracle is clearly attempting to use copyright as a shield for what more properly is a tool, not the expression of an idea. Much in the way that while you can copyright the combination of typeface, layout, and graphic elements in a phonebook, you cannot copyright the names of businesses, numbers, or the particular order in which they are presented. In short, you can't copyright an idea, fact, or a system - you can only copyright a particular expression of those things.
I'll leave you with a tidbit from the 1976 Copyright Act that I think sums up the absurdity of Oracle's argument rather nicely.
In no case does copyright protection for an original work of authorship extend to any idea, procedure, process, system, method of operation, concept, principle, or discovery, regardless of the form in which it is described, explained, illustrated, or embodied in such work.
17 USC Sec. 102 (Copyright Act, 1976)