Yesterday, there were few French papers talking about iPhone 4th Gen rumors and today its Korea Times turn. Yahoo finance has cited Korea Times claiming carrier KT has revealed the following specs. (Sorry, looks like Yahoo finance has removed this page)

They said the coming 4G iPhones will be equipped with organic light emitting diode (OLED) screens on surface and live video chat functionalities, while removable battery is highly likely.
The new 4G iPhone is also going to be loaded with dual core processors and higher and powerful graphic chips that can deliver higher video resolutions and better “still” images when taking pictures.

I wish all of these rumors could come true. But going by rumors that made rounds before the launch of iPhone 3G and 3GS, even if 50% of these rumors come true, I would be grateful.
[UPDATE]
Macrumors covered this story sometime back as well:

A new report today from The Korea Times claims that Apple is preparing to launch the fourth-generation iPhone, with sources claiming that it could debut as early as April. The assertions apparently come from an executive of KT, the exclusiveiPhone carrier in South Korea, who claims that the new iPhone will launch to large Korean corporate clients in April, with release to the general public occurring in June. Such a move would be odd for Apple, which has relied on the publicity and excitement of itsiPhone launch events, a tactic that would be undermined by early availability of the handset to a limited customer base.