Sony officially announced that the PS4 Neo is a real project they are working on and will be detailing in the future, but they will not talk about it or show off the updated version of the PS4 this E3.
Source: NeoGaf VIA FT 
More comments from Andrew House on the subject:

Andrew House, president and global chief executive of Sony Interactive Entertainment, told the Financial Times that the “high-end PS4” would be more expensive than the current $350 version.
“It is intended to sit alongside and complement the standard PS4,” he said. “We will be selling both [versions] through the life cycle.”
The new console, which is codenamed “Neo”, will target hardcore gamers, he said, as well as consumers with a 4K television set looking for more high-resolution content.

However, in a move that may disappoint some fans, Mr House said that Sony would not be unveiling its new console next week and refused to say when or at what price the unit would go on sale. “We want to ensure we have a full range of the best experiences on the new system that we can showcase in their entirety,” he said.
Nonetheless, he downplayed concerns that the move would cause interoperability problems between the old and new PS4 hardware.
“All games will support the standard PS4 and we anticipate all or a very large majority of games will also support the high-end PS4,” he said.