Not according to the courts. Psystar's attempt to defend itself by attacking Apple as a monopoly in "Mac OS X compatible computers" was thrown out of court on its ear. Apple is a monopolist only in the same way that Honda is a monopolist in reference to Honda automobiles. Economically and legally one cannot be a "monopolist" for its own copyrighted or patented products. One can only be a monopolist in reference to a "market."
Sooo many levels
http://www.applematters.com/article/has_apple_finally_become_a_monopoly_like_microsoft/
The psystar case is ongoing,, too.
http://blog.wired.com/business/2009/03/apple-denies-os.html
http://windowsitpro.com/article/articleid/94761/apple-faces-federal-monopoly-suit.html