The Lytro camera will let you focus your pictures after they've been taken (and see around the edges...)

It will also let you see around the edges of foreground objects... I'd read a bit about the Plenoptic/Light-field camera before but hadn't quite got my head around the physics. Lytro is a spin off from Stanford

Interesting news via Charlie Sorel at Wired:

"...Ng’s company Lytro is planning on launching the camera this year.
Regular Gadget Lab readers will recognize the technology as a a
light-field, or plenoptic camera. These camera put an array of
micro-lenses over the sensor. This lenticular array sits on the focal
plane of the camera (where the light is focused by the lens — also known
as the film plane), and the sensor sits slightly behind.

Thus the camera not only records the color and intensity of the
light, but also the direction. Using some heavy processing, this
information can then be used to do the magic you see above. It also
replaces much of a camera’s precision mechanics with software.

While this after-the-fact focus choice is the clear wow factor, there
are other neat tricks the camera can do with this information. First is
that the camera can shoot in much lower light. Second is that, as the
sensor is recording direction information, you can peek “behind” the
edges of the foreground objects...." (more).

From Lytro:

The Science Inside

Light Field Defined

What is the light field?

The light field is a core concept in imaging science,
representing fundamentally more powerful data than in regular
photographs. The light field fully defines how a scene appears. It is
the amount of light traveling in every direction through every point in
space – it’s all the light rays in a scene. Conventional cameras cannot
record the light field.

Light Field Capture

How does a light field camera capture the light rays?

Recording light fields requires an innovative, entirely new
kind of sensor called a light field sensor. The light field sensor
captures the color, intensity and vector direction of the rays of light.
This directional information is completely lost with traditional camera
sensors, which simply add up all the light rays and record them as a
single amount of light.

Light Field Processing

How do light field cameras make use of the additional information?

By substituting powerful software for many of the internal
parts of regular cameras, light field processing introduces new
capabilities that were never before possible. Sophisticated algorithms
use the full light field to unleash new ways to make and view pictures.

Relying on software rather than components can improve
performance, from increased speed of picture taking to the potential for
capturing better pictures in low light. It also creates new
opportunities to innovate on camera lenses, controls and design.

If this is technology that really does prove practical and scale-able then it has the potential to quite radically change photography. It's also a nice reminder that photograph isn't a picture of a thing, but a recording of light. "Now how much reality is there in that" as David Hockney once said of photography...