Following on from our US-based correspondent Mike Elgan's excellent list of unanswered questions about the iPhone, 20 things we don't know, here's three more for us in UK.

1. How much will we have to pay for an iPhone? Apple hasn't released details of UK pricing, and the US pricing of $599 (£307) for the 8GB model and $499 (£256) for the 4GB phone -- with a tie-in to a two-year Cingular mobile phone contact -- actually gives no indication towards what we'll pay in the UK.

Phones are much more heavily subsidized over here. For example, the popular Sony Ericsson W850i Walkman phone -- the best music-playing phone so far, though that's not saying much next to a proper iPod -- is free with a 18-month contract on Vodaphone. On Cingular, it's $74.99 (£40) after a complicated mail-back rebate system that'll cost you an extra $100 up front -- and you're tied in for two years.

The other issue is the high exchange rate between the Pound and Dollar -- which is currently at almost two dollars for every pound -- so UK prices will never be as low as a simple conversion would make you think. To pick one example, Adobe's Photoshop CS 2 is £485 plus VAT in the UK, but $649 (£335) without tax in the US. US prices are published without tax due to differing rates in different states, while UK prices for consumer goods almost always include tax (VAT), so the perception of poor value can be quite high.

It's possible these two factors will cancel each other out to end up with a price similar to a direct conversion -- but that's a possibility not a probability.

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<b>2. Will we have Yahoo push email?</b> Contrary to what Steve Jobs implied at his keynote, Yahoo

3. What's the competition like? The US gets the iPhone in June, but we won't see it until near Christmas. That's enough time for another company to realize -- if they don't know already -- that a consumer-focussed smartphone is likely to be more popular than the business-focussed ones they've produced so far. Devices such as HP's iPaq hw6915 Mobile Messenger are great for business people (or journalists) on the move -- but the consumer values an intuitive music-playing system and other fun functions over the ability to view PowerPoint presentations.

Sony would be the natural contender to add a 4GB or 8GB flash media drive to a new model in its Walkman line -- though an interface overhaul would be necessary to compete.

The iPhone is the first true smartphone for a life outside work, not just outside the office -- but let's hope it's not the only one come Christmas.