IMPORTANT NOTE: Since version 2.10 Genymotion includes native support for Google Play Services and Google Store. Just open the emulator and click in the "Open GApps" widget showed in the toolbar.
Simply download and install Genymotion 2.10 and a new “Open GApps” widget will be available in your toolbar. Click it and it’ll do the rest! Now you can have your applications relying on Google Play Services and Google Play Store working