Last year, Apple surprised everyone, including other mobile chip companies, with the 64-bit A7 chip, which was based on the new ARMv8 architecture. The others were surprised because no one expected ARMv8 chips to come out until this year. That was a serious miscalculation on their part, which later forced the companies to scramble to release an ARMv8 chip as soon as possible, too.
From the looks of it, Samsung was already planning to release a Cortex A57-based chip on time, which is built on the ARMv8 architecture -- the Exynos 5433/Exynos 7 Octa. The chip is already inside the Galaxy Note 4 (although with its 64-bit mode disabled).
Qualcomm, on the other hand, seems to have been caught by surprise, at least at the high end. At the low end, the company was likely already planning to replace its Cortex A7-based Snapdragon 400 with a Cortex A53-based Snapdragon 410, which is why we're seeing that chip on the market much sooner than the Cortex A57-based Snapdragon 810.
Qualcomm won't have the Snapdragon 810 ready to ship in devices until this spring (likely to appear in the Galaxy S6 and possibly the HTC M9), but it does have a "Mobile Development Platform Smartphone" (MDP/S) based on the chip that's ready to go. A Canadian company called Intrinsyc already has it available for $800.
The smartphone will come with a big.LITTLE octa-core processor (Cortex A57/Cortex A53), an Adreno 430 GPU, Qualcomm's Hexagon V56 DSP, VIVE 2-stream 802.11ac Wi-Fi, Bluetooth 4.1, IZat Gen8C GPS, 4 GB of LPDDR4 RAM, 32 GB of eMMC 5.0 storage, a 13MP camera with OIS on the back, a 4MP front-shooter, a 6.2" QHD screen and many sensors. It will also support external connectors such as USB 3.0, micro-HDMI, 3.5 mm headset jack and a microSD slot.
By getting this developer-focused platform out early, Qualcomm is ensuring that many app developers or companies wanting to build devices with this chip will have enough time to optimize them for Qualcomm's first 64-bit high-end chip.