First Major Update
A free customer update will be made available for all Windows Phones in the first two weeks of March, which includes new capabilities such as copy & paste and faster application performance.
Availability on CDMA Networks
With added support for CDMA networks, Windows Phone will be available to even more customers on mobile operators such as Verizon and Sprint in the first half of 2011.
Twitter Integration in the People Hub
The popular social networking service Twitter will be integrated into the People Hub in the second half of 2011.
Office Document Storage in the Cloud
Document sharing and storage in the cloud via Windows Live SkyDrive will be added to Windows Phone in the second half of 2011.
Next Generation Browsing with Internet Explorer 9
A dramatically enhanced Internet Explorer 9 web browser will be added to Windows Phone in the second half of 2011. It will feature the same standards support (HTML5, etc.) and hardware accelerated graphics as the PC version.
Additional Multi-tasking Capabilities
We will add the ability to switch quickly between applications, run applications in the background (such as listening to music), along with a number of other capabilities in the second half of 2011. Developers will learn much more about this during Aprilâ€™s MIX conference.
Source: Windows Team Blog