Apple has very quietly signed up to the Thread Group, the body pushing the 802.15.4-based low power mesh personal area network (PAN) protocol. It comes in the same week as Thread’s rival, and sometimes good friend, Zigbee passed 500m sales, with projections to hit 3.8bn by 2023. However, the Zigbee Alliance is claiming that it will account for 85% of 802.15.4 shipments, which leaves very little room for Thread. This could be huge news for Thread, especially if Apple incorporates it into HomeKit. However, both Apple and Thread are well behind Rethink’s expectations for smart home progress – although in their defense, the entire smart home sector has underperformed so far, especially in the smartphone market. Apple only really has two devices…