In its motion for a summary judgement, Psystar more or less takes the exact same approach as Vernor, claiming that Apple sold their copies of Mac OS X to Psystar, instead of licensing them, and that as such, the First Sale Doctrine (section 109 of the US Copyright Act) and the Reproduction Exception (Section 117 of the US Copyright Act) apply.
In case you don't recall what these two mean, this is how I put it in the Vernor vs. Autodesk write up: "The first Sale Doctrine dictates that owners of copyrighted material may resell this material, despite the monopoly copyright holders have over said material. The Reproduction Exception states that owners of software may make any copies necessary to use the program. Without the latter, you would be unable to run software without breaking copyright law."
More specifically, the Reproduction Exception states that you are allowed to make a copy (or authorise someone to do so) of a copyrighted computer program, provided that "such a new copy or adaptation is created as an essential step in the utilization of the computer program in conjunction with a machine". Psystar argues that therefore, the steps it takes to get Mac OS X Leopard to run on its computers do not constitute as copyright infringement (Apple's claim), because those steps are "essential [...] in the utilization of the computer program [Mac OS X Leopard] in conjunction with a machine [the Psystar computer]".
Furthermore, Psystar states that because of the First Sale Doctrine, they are allowed to resell copies of Mac OS X Leopard that they legally purchased. Section 109 of the US Copyright Act does not make any reference to it only being valid for individuals, and not for commercial entities (like Psystar); a claim often made by those in support of Apple.
Psystar also dismisses Apple's claim that the clone maker is in violation of the Digital Millennium Copyright Act. "Apple cannot assert claims under the DMCA for circumvention of a technological protection measure because such claims can be brought only when the circumvention is for the purpose of and has the effect of infringement," the motion reads, "Circumvention alone is not a violation of the DMCA; only circumvention to gain unauthorized access to that which copyright protects is actionable."
Psystar further dismisses Apple's claims of trademark infringement, and makes a pretty strong case there, too:
Apple's motion for a summary judgement is pretty much (as expected) the exact opposite of Psystar's. Apple insists that Psystar violates copyright and the DMCA. Apple of course points to its Software License Agreement, and claims that it is licensing its software, not selling it.
Apple's motion dismisses the arguments regarding the Reproduction Exception, but it's all based on the Software License Agreement; heck, even copying to RAM is considered a breach of copyright by Apple, because the computer in question is not an "Apple-labelled computer". Most - if not all - of Apple's claims hinge on the applicability and validity of the terms in its SLA.
The interesting thing is that throughout the entire motion, Apple maintains that Psystar is making illegal copies (the word "pirated" even occurs), but that's only because Apple believes its SLA makes installation of Mac OS X on non Apple-labelled computers illegal. Apple makes it seem as if Psystar only bought like three copies of Mac OS X, and then copied those ten thousand times, and sold those copies. This is of course false, but it is a nice effort to conflate the Reproduction Exception with piracy.
All in all, whereas Psystar's motion is built on the US Copyright Act and some of its exceptions, Apple's motion relies heavily on the Software License Agreement. This case bears a remarkable resemblance to the Autodesk case, and this case is also mentioned in Psystar's motion. In that case, it was established (multiple times) that the AutoCAD software was sold, not licensed. If Judge William Alsup comes to the same conclusion in this case, Apple's motion more or less crumbles like an old cookie.