Microsoft released Dynamics CRM 2013 free mobile apps for Android, iPhone, iPad and Windows Phone devices. At this moment these apps will work only for online CRM.
You can download the app directly from App Store’s:
Dynamics CRM 2013 Mobile Client for Android:
https://play.google.com/store/apps/details?id=com.microsoft.crm.crmhost&hl=en
Dynamics CRM 2013 Mobile Client for iPhone and iPad:
https://itunes.apple.com/us/app/microsoft-dynamics-crm-for/id723891307?mt=8
Dynamics CRM 2013 Mobile Client for Windows Phone:
http://www.windowsphone.com/en-us/store/app/dynamics-crm/bdf6ad14-8ff3-4db1-a9d5-336c50ef13ee
Microsoft Dynamics CRM Blog 