Is it possible to crop multiple pages in Mavericks Preview.app?
Yes.


Open a PDF.
If not already enabled, View → Thumbnails.
Select some pages (click first then select all; command+click or shift+click)
Use the rectangle tool to select region on page. (On versions of OS X prior to 10.9, you should see a preview of the selection on other pages too).
Select Tools → Crop (or Command+K). All your selected pages should be cropped.
Save or Save As.