While Acrobat is copyrighted by Abobe, PDF as a document standard is not, just as Microsoft can't have a monopoly on the .doc extension (although I'm sure they would). Apple was able to reverse engineer the process without using a code from Adobe to make PDFs. In fact, you can also have some web-based technologies make PDFs. PHP, which MacRumors apparently uses, can generate PDF files on the fly. Pretty cool, huh?