In Adobe’s knowledgebase I read, that described phenomen is correct. The reason is the following:

Mac OS X Snow Leopard (v10.6)’s enhanced security features prevent Adobe’s PDF Printer from functioning as it did in previous versions. As a result Adobe Acrobat Pro 9.1 removes the Adobe PDF Printer and adds a new Save as Adobe PDF function. Customers using earlier versions of Adobe Acrobat will find that the Adobe PDF Printer is unusable when running on Snow Leopard.

But how do I create PDF files with Adobe Acrobat? Here’s the solution:

Instead of using a PDF printer in the printer dialog, you just have to use the PDF option in the printer dialog: