Engadget notes that "Apple Mac OS" is listed as a possible pop-up selection when attempting to download the latest drivers for your Dell computer.
The Driver/Downloads page discrepancy, of course, has sparked a lot of speculation about a Mac OS X/Dell pairing. The additional website pick-list option, however, may have simply found its way onto Dell's support site for existing printer drivers which Dell does produce Mac drivers for.
Additional options however do appear under "Mac OS", but all appear to be Windows executables with the exception of the Printer Drivers.
Dell's CEO has publicly stated that they would be "happy to offer" Mac OS X for PCs if Apple were to allow it.