Plastic packaging has long been the bane of environmentalists, who see petroleum-based beverage bottles and shopping bags piling up in landfills as one of the biggest symbols of a wasteful society.

That bad rap for plastic (not to mention soaring prices on the materials that go into making it) has sent consumer products companies scrambling to trim down package sizes and create less waste. We’ve already seen concentrated laundry detergent in smaller bottles, and even Wal-Mart is cutting back on plastic shopping bags.

In the lastest “less is more” packaging change, Arm & Hammer has launched a line of refillable household cleaners with the brand name Essentials.  A starter kit — which looks and costs about the same as a regular bottle of glass or multi-surface cleaner — includes an empty spray bottle and a cartridge of concentrate that is mixed with tap water. When the cleaner is runs out, all you have to do is buy another cartridge of the plant-based concentrate.

Arm & Hammer parent company Church & Dwight says the refills cost about 25 percent less than buying a whole new bottle of the stuff. And what’s in it for them? The company said shipping fewer spray bottles will save them 18 million gallons of fuel.

Smaller natural products companies such as Shaklee already sold similar refillable cleaners, but Arm & Hammer is among the first mainstream brands to roll them out. The are in U.S. stores now.

When Wal-Mart decided it needed an environmental strategy, it asked for help from some of its biggest critics.

The only thing is, the non-governmental organizations it looked to for advice on building a sustainable business didn’t want to ruin their green cred — or jeopardize their relationships with their donors — by admitting that they were working with Wal-Mart.

“We had to guarantee them that we would not ever tell anybody that they were there,” Wal-Mart Chief Executive Lee Scott said during an appearance at the Wall Street Journal ECO:nomics conference in Goleta, California.

Since then, Scott said NGOs have been critical to helping the company understand issues such as sustainable fisheries and carbon dioxide emissions as well as pushing it to go farther in thinking green.

“They are more aggressive than we are, and they push us to go further, but they also have not been as judgmental about our failures as I was afraid they would be,” Scott said.

Next, Scott said Wal-Mart will call on NGOs to help its Chinese suppliers clean up their act.