Some mobile operators see this as their announcement to make. Remember who wears the pants in most carrier-manufacturer relationships — the carrier. In most cases, carriers set the prices because they sell the phones. In many cases, a phone only exists in the first place because an operator has requested or approved it. Motorola’s Droid lineup, for example, is probably heavily influenced by Verizon Wireless. (Heck, “Droid” isn’t even a Motorola or Google brand — it’s Verizon’s.) The carrier can then drag this out for one or two more PR events — perhaps disclosing a price one day, a launch date another day — in an attempt to drum up more excitement and more news coverage. Apple, being Apple, is in the position to demand control over these disclosures. Most of its competitors are not. (Apple also distributes a large portion of iPhones on its own, via its retail empire, which Microsoft and others are now trying to develop.)

Why Does Apple Announce iPhone Pricing And Availability But Other Phone Makers Don’t? - SplatF

As usual - Dan does some of the very  best tech analysis out there.