It's been touched on slightly but I think there could be some truth to the wireless hub concept that has been disussed, however I would offer some tweaks. This "brick" will be an opportunity to move many of the bulky pieces currently in the MacBook (or Pro) to a remote/desktop location would allow for huge space/weight reduction, could increase the storage capacity/performace of the head laptop unit, and would fit with Apple's commitment to simplicity/eliminating wires.
Move the optical drive (to utilize Apple's Remote Disk), a larger harddrive, usb/ethernet/firewire/video connections and a beefed up processor, leaving a slimmed town laptop with the ability to operate either standalone (as a netbook with ssd harddrive) or in tandem with a "brick" as a wireless head unit. This would mean that you could be running your OS on your "brick" and viewing and interacting with it on your screen at your desk (plugged into the brick), on your laptop on the couch, on your iphone, or on your TV with your Apple TV... and we all know how Apple likes integration.
If your sold on the BRICK as an acronym idea... I'm not sure on the B, C, and K, but the RI could very well be Resolution Independence.
Or maybe, as previous posters have suggested it is "B-R-C-K"... which would be Barack with out the vowels, suggesting that Obama will be on hand.
At the end of the day, we'll probably get all hyped up and it will be a "one more thing" with Ben Folds Five being added to the iTunes library (I know, they're already on there).