According to a blog post on Motorola’s official site, The new Natural wood backs will arrive on January 21st. Purchasers that ordered their Bamboo back Moto X through MotoMaker and paid the extra $100, will be issued a refund (in the form of a certificate of $75 towards Motorola accessories).
They have ditched the Rosewood design and now have these selections as of this posting
Remember, the Moto X is now at the low price of $399 unlocked and with an extra $25 you can customize a great phone with some wood uniqueness to show off. Motomaker link is below to check out the wood designs.