Oooo, suspense-- the force that makes the world go 'round. For example, take that mysterious Mezzanine slot on the iMac's motherboard. It's a PCI-based variation of Apple's own personality card slot architecture, meaning that it could theoretically support just about any function you can stick on a PCI card. The mystery is, why is Apple keeping so quiet about this magical slot that could eliminate so many of the iMac's perceived shortcomings of unexpandibility? In public, they rarely even admit that it exists. In private, they not only haven't released specs on the proprietary slot to hardware developers, but they've also flat-out told those developers not to create anything that uses said slot. In fact, Apple went so far as to remind the buying public that any "unapproved" modifications to the iMac's motherboard (such as installing a Mezzanine card, nudge, nudge) would void the system's warranty. So why the cover-up?

The earliest rumors as to the reason for all the hand-waving indicate that Apple has its own plans for that slot, though no one seems to know what those plans are. We've heard dark whispers of an Apple-branded DVD-ROM upgrade kit, which relies on a Mezzanine card for the MPEG-decoding hardware. Other parties claim that Apple's preparing a TV tuner and video in/out system for the iMac, allowing consumers to digitize and edit their home video footage using that Final Cut software that Apple bought from Macromedia several months back. A variation on that rumor states that the card is actually a FireWire card, which allows the transfer of digital video data directly from newer camcorders equipped with a "DV OUT" port; the beauty of FireWire, though, is that it also allows the use of high-speed data devices, like SCSI but faster, more reliable, and more flexible. None of these rumors has really developed beyond the whisper stage, but NoBeige indicates that, whatever it is we're waiting for, we should see it in time for Christmas, so the mystery may not endure all that much longer.

Incidentally, despite Apple's warning, several hardware vendors are proceeding with plans to ship expansion cards destined for the iMac's Mezzanine slot. The most intriguing right now is Formac's combined SCSI/TV tuner/video-in module, still in the works. As for currently-shipping enhancements, Griffin's iPort, a serial port and external monitor solution, is now available, and while it reportedly doesn't use the Mezzanine slot itself, it does take up the space provided for Mezzanine cards. So if you own an iMac and you plan on getting one of these third-party Mezzanine cards, just keep in mind that you'll have to choose between it and whatever Apple plans for this "Christmas surprise." (We're keeping our fingers crossed for an iMac-controlled espresso machine-- are the elves in Santa's hardware labs listening?)