ONE STRANGE THING about any Web-based movement is that the "tribes" they create are invisible. This leaves you wondering: Do these people actually exist?

In Grist's case the answer is yes, as I witness two weeks after my Seattle visit at the "Meet, Eat, Drink" party for Gristies in San Francisco. Roughly 300 young, fashion-forward urban professionals are packed into an industrial studio in the SoMa district, chatting each other up under a giant steel dragonfly that sways to the beat above the DJ station. They're quaffing Square One organic vodka and organic Mendocino merlot and loading their plates—made of cane fiber recycled from sugar mills—with skewers of organic chicken satay.

The average attendee seems to be a spunky, athletic 28-year-old woman who makes a good living in "the green space." Like the tipsy Susannah Churchill, a renewable-energy analyst for the California Public Utilities Commission, who's decked out in hip-huggers and a sheer pink tank-top and who declares, "I'm a clean-energy dork!" in such a disarming way that you wish the world were overflowing with clean-energy dorks. That is, until you get buttonholed by the hyperkinetic Mark Dixon, a nice guy who persists in detailing the plans of his YouTube-inspired site, YourEnviron- mentalRoadTrip.com.

I'm introduced to an Asian American woman known by her nom de blog, "green LA girl," who uses her site to dish about "Fair Trade coffee and ethical consumerism in Los Angeles." She drove up for the weekend in a vintage yellow Mercedes fueled by biodiesel, delivering the car to a friend who'd bought it on eBay. She's wearing secondhand Prada, a recycled rubber belt, and a dazzling white overcoat. Like all the regular Grist readers I meet, she serves up a bite-size rave about the site.

"Zany and funny," she says, "but it gives you all the information you're not getting if you're just reading the L.A. Times."

I seek out one of the lonely graybeards in the crowd. Dwight Collins, a tweedy 60-year-old professor at the Presidio School of Management, which offers an M.B.A. program in sustainable business, confesses he's never read Grist, but it's clear to him that all these people are "part of the sustainability movement," which he differentiates from the "environmental" movement.

How so? "Sustainability," he says with a wink, "equals profit."

At every turn, someone's chatting up their business plan. It's like the dot-com nineties again—except that the familiar irrational exuberance is now juiced with altruism. Consider, for example, Amy Tucker, the nattily dressed inventor of a kids' trading-card game called Xeko, which is like Pokémon, except Picachu is an endangered dwarf lemur, and the goal is to collect enough cards to build a complete "Xekosystem."

The only partier I meet who's second-guessing any of it is Anna Cummins, a 33-year-old from Santa Monica who runs BringYourOwn.org, which encourages you to lug reusable mugs and bags to cafés and markets.

"I love Grist," she says, tipping back an organic IPA. "But there's this strain in the green world of 'Oh, you can consume. It's OK, 'coz its green.' When, really, you just need to consume less. To me, that's the one slight downfall of–"

We're interrupted by a Grist staffer at the microphone, thanking Square One, Clif Bar, Organic Vintners, Bison Brewery, and the other sponsors. The liquored crowd roars with approval. The staffer starts handing out T-shirts ans announces the grand-prize winner of the evening's raffle, a six-month membership with car-share company Flexcar.

By now it's 9 P.M. and the party is dying down. Green LA girl, her white coat stained with merlot, is gathering troops to go to a party hosted by Common Vission, a group that tours California in veggie-grease-powdered buses, planting friut saplings and teaching schoolkids about what its Web site calls "sustainable ecology, West African agricultural drumming, and earth-conscious hip-hop."

"You want to go?" David Roberts asks Lisa Hymas.

"I don't know," she says with a grimace. "It's a little too hippie for me."

Roberts sees me taking notes, and his eyes widen in mock fear. "But, Lisa," he says in his sternest Homer Simpson voice. "Remember? We lovvve hippies."