You may have noticed recently that upon booting into your Chromebook and quickly checking settings that there is a features that is new. A check-box will appear that will give you the option to "Enable Android Apps to run on your Chromebook." As of yet, the feature doesn't work, but it is coming - probably sooner rather than later - and it will be handy. No more will you have to run or test applications on your actual mobile device - you can run them from your Chromebook. This will be a handy feature for developers, but I'm not sure how mainstream it will ever become.
Users can currently download and run a handful of Android apps from the Chrome Web Store. From the screenshot, it appears that Google will be using the more familiar Play Store to distribute and sell apps. Current Android users will likely be able to log-in and access their already purchased apps.