Great, the LA Times pulled the story from the link.

The story was of an aftermarket company which is making an add-on kit for the Prius which adds batteries and a plug in capability. It also "fools" the computer into thinking there is more juiced available, thereby delaying the time the gas motor comes on.

They report up to and over 150 mpg. Kit cost is still high, near $10k. But if Toyota were to adopt it as an option, the cost could drop as low as $2k. If I can find the company link I'll post it.