That's not strictly true. If you look at the purchasing power of the pound sterling, you see that it is nearly 15% stronger than the dollar. You're also not taking into account taxes. The UK prices are really:
Mac Pro: £1445.96 ($2841 USD) vs. $2499 [13.5% markup]
MacBook Pro: £1148.09 ($2256 USD) vs. $1999 [13% markup]
etc.
Taking into consideration the weakness of the dollar, the UK prices aren't much higher at all, especially since the actual costs of conducting business abroad are also higher, so some markup is to be expected. However, with a stronger dollar, you'd see extremely similar prices to the US retail price (before VAT). A ten cent reduction in the exchange rate cuts the US-equivalent price down to $2700, which is in line with what you'd expect. Here in the US, we pay through the nose for UK products as well. Pricing of American products abroad is the one downside to a weak dollar from your perspective.
The UK's tax policies are not Apple's fault (nor any other US-based retailer who does business in the UK), nor should Apple be expected to lower prices to compensate for your higher tax rate. You also can't necessarily expect a company to revise prices daily to keep up with exchange rates.
While the prices of Apple products in the UK aren't that much higher than the US, you can't just avoid adding VAT to the prices when comparing, as not all of the United States pay tax on sales, do they?
And for all your good points about the strong pound, and the relatively weak dollar, how does that explain that the Adobe CS3 Master Suite is double the price here, unless you buy the Academic version - which is $80 cheaper in the UK than the US?
It's corporation greed, that's what it is.
And I've still not had sufficient proof to convince me otherwise. Tax & currency don't quite cut it when the prices are just *that* different.