The lower RAM footprint may be viewed as an attempt by Microsoft to make their mobile OS more compatible with cost-conservative phones.
In light of the current partnership between Windows and Nokia, it makes sense that Microsoft would want to improve Windows Phone OS amongst mid-tier mobile devices such as those offered by Nokia.
While official specs list 256MB as minimum system requirement, most current Windows Phones utilize 512MB.
Another added feature in Tango is the ability to sort applications in folders on the start screen, which should make finding apps easier and the start screen less cluttered.
