E Inks are not the only next generation display technology that can be used to make flexible, power efficient displays. Another option is rollable (flexible) displays using OLEDs.
OLED (Organic Light Emitting Diodes) are made from materials that emit light when electrical current is applied to them. OLEDs do not require a backlight - which means that OLEDs are very thin and efficient.
OLEDs can be used on a flexible substrate - they can even be made Rollable.
So OLEDs can be used to create a large display, but still take very little room inside a mobile phone or PDA or just be used as a standalone rollable monitor.
OLEDs are used today inside many cellphones and MP3 players - as 'normal' displays. Flexible OLEDs are still very difficult to make and are in the 'research' phase. We can expect flexible/rollable OLEDs in about 5 years or so.
OLED TVs are also just starting to appear, with Sony's XEL-1 OLED TV released at the end of 2007. But this TV is expensive and small (11", at about 2,500$) so it can't really be considered a commerical OLED TV...