Though Toyota, General Motors, and Honda generated high volumes of positive conversation among online bloggers concerned with environmental sustainability, organic grocer Whole Foods received the most good buzz.

Some 78 percent of mentions about Whole Foods were positive, according to a JD Power and Associates analysis of 40 million blog posts over the past six months.

Organic food and beverages in general tended to get good reviews in the blogosphere: Eight in every 10 mentions involving organically-inclined companies and their products were positive.

A recent Nielsen Online report showed that eco-sustainability buzz increased 50 percent from 2007.

Also overheard in the blogosphere:

• Food prices were a hot topic of discussion, with a particular focus on making conscious choices about food as a way to both impact the environment and improve health and reduce illness.
• Biofuel is out: Most consumers expressed disdain for diverting corn and other food products into biofuel production.

Other highlights from the report, regarding specific brands:

• After Whole Foods, Home Depot received the second-highest percentage of positive mentions.
• Wal-Mart, which initiated a big move in the retail space with its commitment to "go green," generated the second-highest amount of total volume of mentions, but had lower-than-average positive sentiment. Sustainability discussions comprised just two percent of overall "Wal-Mart talk."
• Safeway and Costco each generated over one percent of total sustainability discussions but had lower-than-average volume and a lower-than-average proportion of positive sentiment compared with other brands in the industry.

No brand in the CPG category received more than one percent of food and beverage-related conversations regarding sustainability. However:

• Seventh Generation and method generated higher-than-average proportions of positive discussion about sustainability in the cleaning products category.
• Clorox drew a large amount of overall discussion volume, with a slightly lower-than-average percentage of positive sentiment.
• Niche brands Dr. Bronner's and Ecover generated more than 1% of total cleaning product conversations about sustainability.

Consumer expectations from brands are escalating. They not only expect eco-friendly products, but demand that company policies and procedures support environmental sustainability, the report said.

PepsiCo, for example, recently launched two websites geared to promoting environmental awareness and urging users to become more active.

PepsiEcoChallenge.com plays off the brand's "Pepsi Challenge" but "goes beyond the cola wars" to show what the company is doing to promote sustainable energy use, water use and product packaging, explained Victor Mendez, PepsiCo North America VP Marketing.

The site outlined goals of reducing electricity and water consumption by 20 percent each and fuel by 25 percent by 2015.

And PepsiRecycling.com offers Pepsi points — a popular program where customers collect and redeem points for merchandise – in exchange for a consumer recycling pledge.

In April, Pepsi introduced the "Have we met before?" campaign, posting the message on 750 million cans per month, which was supposed to remind its customers to recycle, writes Ad Age.

Still, the most memorable Pepsi messages likely remain those from poster boy Justin Timberlake.