This is huge news: certainly nobody expects Apple to make its Apple Watch compatible with your Samsung Galaxy S6, but Google has done the reverse, making its wearables platform compatible with its rival's top-selling smartphones.
Granted, there are limitations, both in hardware and software alike. On the hardware front, the only watch currently on the market that officially supports the iPhone is the LG Watch Urbane. However, all future watches - including the Huawei Watch (shown above) and Asus ZenWatch 2 - will support iOS right out of the box.
Google wanted to ensure that anyone could buy an Android Wear watch and pair it with an iPhone without needing an update; that's why older watches aren't on the list. Yet The Verge tried its updated Moto 360 with Android Wear 1.3 installed, and found that it worked perfectly. It's not yet known if this will apply to all up-to-date watches, but it's worth a shot if you have an Android watch and an iPhone.
As for software, the experience is limited compared to what an Android Wear watch can do on an Android phone, and certainly compared to what an Apple Watch can do. Basic notifications work for emails, texts, and calls, plus you'll get Google Now cards and can use voice commands to perform searches or create reminders.
Fitness tracking with Google Fit also works, plus there are a few native apps on the watch and Google's own apps - like Gmail and Calendar - deliver ritzier-looking notifications. And you'll be able to install some third-party watch faces, as well, from a curated selection found in the iOS app.
Google's Android Wear app is now available for iPhone to facilitate the process, and surprise - it's actually called "Android Wear," despite Apple's rules against referring to competing platforms. Perhaps Apple sees the benefit in letting people stick with their iPhones but opt for alternative watches. Whatever the case, today's news is a big step, and we'll surely see plenty of new Wear watches with iOS support (like the Moto 360 successor) in the coming months.