As far as iPhone hype goes, I never rode the bandwagon. The cell phone market is a completely different beast than the MP3 player market, and same rules do not apply here.
Although (for some strange reason) none of Apple's competitors in the multimedia player market managed to create an equally intuitive user interface, when it comes to cell phone UIs, Nokia, Sony Ericsson and others call the shots - and people who use cell phones - and that's pretty much all people - are used to their UIs. So, fancy touchwheels won't be much help here.
Furthermore, while iPod is popular all over the world, Apple is strong only in the US. Here's an example. In Croatia, where I live, I reckon 3 out of 10 people on the street would know what an iPod is, but maybe 1 in 20 would know what Apple or a Mac is and what they do. On the other hand, they all know what Nokia is. Croatian market is a small one, but this is indicative for all other eastern-european countries. So, I reckon, while it may not be the case in the US, that the rest of the world might react to the news of iPhone rather mildly.
There are also those pesky things called mobile operators, which kinda own much of the cell phone market right now. Apple has to reach an agreement with them, because if they don't support the iPhone, including it in their device+subscription cheap bundles, it will be a lot harder for iPhone to get wide acceptance.
If you ask me, the multimedia-player-meets-cell-phone functionality is where Apple needs to make a breakthrough. Althouth all big cell phone manufacturers have multimedia capabilities in their products, none of them has been able to really nail it down perfectly yet. Photo functionality? Sure. Video recording? Yes. Occasional MP3 listening/video playing? Well, sometimes, but not really. If iPhone manages to offer a good cell phone with great multimedia player capabilities (and I mean great, not just good enough), it might have a chance of a big worldwide impact.
All this said, let's wait for monday and see if Gizmodo was right about the launch in the first place.