Just a rumour at this stage; but whispers suggest Sony are planning to introduce at redesigned PS vita model at the Tokyo game show.
The redesign is said to incorporate a new larger 6.3 inch oled screen, made by Samsung, and looks set to feature a ram increase too. Currently, all Vita units come with 513 mb of ram but the new design would ship with 1gb. Games are said to remain locked to 512 though so any ram increase would only be there to allow the os to run more apps in the background. Better ps4 integration maybe?