The funny thing is: We all know that on 8th, we will meet here and bitch about Apple how they could do such a hype! It was the same with the last keynotes and with the iPod. The expectations are high, everybody thinks that all the dreams he has will be released.
I *guess* that Apple releases a completely new system architecture: New cpus (maybe G5), new RAM (RamBus or DDR), new external BUS (GigaWire/USB 2), new cordless stuff (bluetooth keyboards and speakers) etc. etc. Note, this is speculation, but maybe Apple only wants to celebrate that they again are back on the olymp of the hardware world.
Still, I am sure they are extending their digital hub thing...it won't be called iWalk, but damn, an Apple PDA could be so cool, and if you take a look at PocketPC 2002, stuff like a dock could really be realised on a PDA, and on a PDA, a OS X style dock would rule big time!
We all don't know...that's why it is so much fun to guess