While everybody outside of the US has been able to mix and match iPhone and wireless operator, the iPhone was still tied to a single carrier in the US. Today, Verizon and Apple
announced the much-hyped Verizon iPhone 4. While the rest of the world collectively yawns, this is good news for American consumers, since there will be more competition, and thus, more choice.
Edit: Eh, the other way around. First choice, then competition.