Last fall, Google released a tool called 'Arc' that allowed developers to run their Android apps in Chrome OS. Soon after, it became clear that Arc's functionality would expand to other platforms, like Linux, Windows, and Mac OS X - basically, any platform that has a Chrome version available.
As Ars technica relays, we can see that Google has begun to really ramp-up its rollout of Arc. At first, developers that ported their apps directly to Arc worked with Google directly, but now, developers can take it upon themselves, submit the app to the store, and relish in the fact that they're able to support another platform without much hassle.
What makes that possible is a tool called Arc Welder, a conversion app of sorts. Even if you're not a developer but have access to an APK, you should be able to use this app to see whether or not that one you're trying to convert actually works fine through Arc. The more feature-rich of apps out there will require the developer to make changes, though, as a simple conversion will not add all of the necessary hooks for use with Google Play Services.
Android "emulation", if I may call it that, is nothing new. There are products like Bluestacks and DuOS that have allowed people to run Android apps on their PC for some time. But, when given an official option, it's hard to ignore, especially since no one is more capable of making Android on the PC work better than the owners of that ecosystem.
For regular users, there's not too much to get excited about right now. As Arc catches on, and the app store fills up, it could prove to be an incredibly useful addition to Chrome.