iPhone tends to get an upgrade in early summer, July at the latest. Not sure about the Touch, but the other iPods gets an upgrade towards Christmas.
As for what the upgrade will be ... double the resolution. I'm hoping for more, but Apple makes great money from incrimental upgrades. There are a million better phones out there, and Apple is continually rewarded for their half-assed upgrades.
I have the original iPhone, and I love it. But there are some glaring omissions on that thing that are pretty much unforgiveable. And I saw no need to upgrade (And pay more a month) for the two revisions. Though the 3G S was tempting. Faster loading on apps would be a plus. Apple may get me to buy the new phone if there are significant changes, but I don't see that happening. I think we look at the iPad to see what to expect ... and what we won't get.
We won't get multitasking. Scratch that, we already have multitasking on the iPhone, but not 'true' mutlitasking. I mean the phone can play music while you do other things. What it can't do, is have two apps open at once. And this will not change. For some reason Steve Jobs has this aura about him. He's so cool and hip, yet he's become more and more controlling over the years. They will not allow third party apps to multitask. Their excuse, 'save battery life' the reality, they want to control every aspect of their product. The upside to this, is they can control the software on their phone. To control quality. The downside of this ... they control every aspect of their product. And stifle innovation.
So at best, we can expect to see the new phone having double the resolution to compete with the newer phones. But overall, not much else. I assume the iPad processor will make it's way into the iPhone. We won't see a change in form factor. Or any 'openess' on Apple's end. Why should they? They'll be sold out of the phone for the first three months. And sell well the rest of the year. Again, Apple is being rewarded for their controlling behavior.
I of course would love to be wrong about this. Again, I love the touchscreen. I love all the third party hardware support (I use a JBL radial speaker at work. Which charges the phone as I listen to music) thanks to sharing the same docking pin as the iPod. I'm just let down by the lackluster upgrades since the original. Hell, the 3G wasn't even an upgrade. It was more "This is what the iPhone should've been in the first place"