Magic Trackpad and Keyboard update to BTLE

What is apple waiting for on updating the trackpad and keyboard to BTLE?

These peripherals have some of the worst battery life I have ever bothered with, the trackpad lasts me about 4 months and the keyboard I would guess about 2-3. Contrarily, the old Microsoft Arc keyboard I had, which used AAA's instead of AA's, lasted about a year (USB dongle instead of BT)

With BTLE becoming the standard in phones and other mobile devices because of the superior battery life, why would they not update the keyboards/trackpads to this tech? Is there a reason (such as incompatibility with older BT Macs, I thought the BT tech was backwards-compatible)