I'm waiting for the dust to settle
iPhone 3GS prices on ebay tanked after the iPhone 4 was announced at WWDC, then it's only yesturday since the prices were released that they went back up. Because the iPhone 3GS is now 8GB and £419 unlocked, it puts people with 16GB/32GB 3GS that are unlocked with warranty in a good place. Especially when the 8GB 3GS becomes more mainstream.
I have an almost mint condition white iPhone 3GS 32GB, fully boxed, officially unlocked, 12 months Applecare left with a dock and incipio feather case. Judging by prices, i should get £360/370 for it when i come to sell it in 3/4 weeks.