Let's go back in time and see what Apple has done at the September Media Event over the past few years.
9/7/05
- iTunes 5
- Motorola ROKR
- iPod nano replaces the mini
9/12/06
- iPod video
- iPod nano update
- iPod shuffle update
- iTunes 7
- downloadable videos (Apple Music Store becomes the Apple Store)
- Apple TV
- One More Thing: movies
9/5/07
- new colors for shuffle, woohoo
- nano update
- iPod classic
- iPod touch
Seeing a pattern here? Apple holds their September Event to promote their iPod lines and to announce new iTunes services.
My predictions are relatively conservative: We'll see iTunes 8, and all of the iPods will get a significant upgrade. I think the iPod nano pictures that have been leaked to us are fakes - the curved screens are really ugly, and their glossiness will be distracting.
Notice how Apple hasn't done anything yet to the iPod Touch despite the iPhone 3G's release two months ago: they're clearly trying to categorize it separately from the iPhone brand. GPS is likely if only because so many App Store applications rely on the positioning API.
Apple really believes in its product line differentiation and won't muddy the iPod-centric September event with notebook news. If MacBook upgrades are coming, Apple will wait until later to announce them - probably in October or November. Capella won't be out until the middle of 2009, and that's just too long to go without an upgrade. They'll do a Penryn bump with a form factor change for now, then advertise Capella's blazing speeds in 2009.
I have no idea where the iTablet fits into any of this. If it's being sold as an iPhone variant, we might hear some news in September. But it's probably going to be marketed as something else, with web browsing and multitouch as the main selling points; remember that the iPhone was originally codenamed "Safari Pad". I do think it's coming at some point; netbooks are finally taking hold in the marketplace, and Apple, fueled by over a decade of research, is going to master it.