iPhone nano
Tell me if you can find a fault with my logic.
1) There is a business case for Apple making a cheaper phone that can be sold pre-paid.
2) Cheaper in Apple's dictionary is not the same as "budget". The only reason said phone will be cheaper is because it will contain less components, (and less expensive components). They will still have a healthy profit margin on whatever they produce.
3) If the device is going to have less on-board storage (say 4Gb or 8Gb), so it has to have a way of letting people have access to all their stuff. This smaller cheaper iPhone therefore had to wait until iCloud was up and running.
4) There is a business case for Apple making a smaller phone - whatever this model is, it will not be just a cheaper iphone 4, or an iPod touch with a 3g antenna. Apple must differentiate it from their current offerings - it should be a different category of device.
5) When Apple created the iPhone, then the iPad, they used the fundamentals of OSX, but they needed a new interaction paradigm.
6) The iPhone/iPad have applications, but these are for fixed resolution screens, and will not work on anything smaller.
7) The rumors tell us that Apple is working hard on a new interaction paradigm: Voice control.
8) Apple already produces a smaller device with a touchscreen and a cut-down version of OSX with voice-over capabilities: iPod Nano. They already produce headphones with a built in microphone.
9) Rumors also tell us that Bluetooth has a new low energy format which Apple has access to.
To state what I think at this stage is bleeding obvious: The iPhone nano will be to the iPod nano what the iPhone is to the iPod touch. How good the product is will depend entirely on how good the voice recognition/AI is, but it will be a smaller, cheaper iPhone, which gives you access to all your data through iCloud (email, contacts, calenders, rss feeds), as well as all your music. It will save battery life by being primarily a voice-control/voice-over phone, but if you want to use the screen you will have your clock apps, stocks, weather (and all the other Apple deisgned apps). Perhaps in the future they'll let developers develop for it too, but everything will be geared towards long battery life.
The reason the Nuance voice over partnership wasn't announced at WWDC was that it made more sense to talk about it at the launch of the next phones. It will be awesome in itself just to have advanced voice control on the iPhone 5, but it will be what makes the iPhone nano possible.