Google had stated that every 6 weeks they send out a new version of Play Services in an attempt to keep the back-end of all Android products and up-to-date. This must be the sixth week because Google has just announced their latest rollout on their blog. Play Services 6.1 adds goodies such as Enhanced Ecommerce analytics and updates to the Drive API.
The last update to Play Services was 5.0 launched in July, and now with the 6.1 update we can see what the Google team has been working on. First we have improvements to Enhanced Ecommerce, which is an analytics extension that provides insights to shopping behavior before a consumer buys as well as showing product performance. The update includes support for Google Tag Manager which will allow devs to monitor and update tags on the go (ie. on your mobile device).
Next we have refinements to the Drive API, including a new Completion Events feature which will allow you to see when actions have been committed to the server and respond to conflicts more quickly than before. You’ll also notice that some Material Design elements have been incorporated into the UI, such as Recents and Starred views.
Last up we are shown a refresh to the Google Fit Developer Preview so you can test any of your fitness apps on any Android device. It should be known that changes to the Preview and being committed very often.
Developers, you should be ready to dive into to all these changes once the app is updated on your end, which is usually a silent update. Hopefully the next six-week update is revealed along with the public release of Android L.
Source: Android Developers Blog