As a footnote to the unlocked iPhone 4 story, it’s worth noting that the average Apple store pricing for UK and France is around $824 (assuming equal blending between the two countries and between the two models). Excluding corresponding VAT leads to an approximate ASP of $695.
Operators probably get a slightly better price so my estimate for the iPhone 4 ASP of $600 seems reasonable with potential upside based on product and regional mix.