Does anyone have experience with buying an officially unlocked iPhone 4 in the US? Does anyone has experience buying an iPhone 4 to be unlocked (oficially by Apple) in the US?

iPhones are unlocked by Apple, after you request the unlock to your carrier (once you have paid the subsidy). Since Apple Stores allow buying iPhones at full price now (for gifts, for example), can I buy an iPhone in an Apple Store and immediately after call AT&amp;T to unlock it?

This should be both legal and possible. Heck, even Apple could offer it in their stores. Does anyone have experience with this? Any tips on how to ask for the unlock to AT&amp;T?
No, this isn't possible to do through official channels. The officially unlocked phones are unlocked from the manufacturer; this isn't possible to do after the phone has been provisioned (otherwise the iPhone hacking community would be all over this avenue rather than going after security holes in the baseband to achieve the same effect). Because if their agreement with AT&amp;T, Apple does not sell these units in the US, and every distributor outside of the US has to agree not to sell the units to US customers.