Windows Phone 7.5 codenamed as Mango was announced in February 2011 at the Mobile World Congress. The Skype application is included in this version. Windows Phone 7.5, the latest build delivers an onslaught of features -no less than 500. Windows Phone 7.5 Mango has multitasking capabilities.
• Dynamic Live tile information
• Full IE9 browsing
• Skydrive and Office 365 documents sync
• Location awareness icon
• Great Twitter integration
• Export and manage contacts to SIM card
• Support for low-cost devices with 256 MB RAM
• Low clock CPU
• Better media messaging
Source : Techradar