- Open a pdf file, or several pdf files, in Preview
- Set it to display thumbnails of the pages in the Sidebar (under View)
- Select the thumbnails of the pages you'd like to print, in the usual ways. You can select pages in several different pdfs, or indeed all the pages in different pdfs. A way to combine images into one pdf file.
- Tell it to Print - either cmd-P or File > Print
Then you can either print just the pages you want, or save them as a new pdf.
If you're still in Snow Leopard (OS 10.6) then to print selected pages, select as above, and the command is in the File menu below Print.