They met by night, in the glow of a Wells Fargo ATM.

Twenty men ages 20 to (if you count me) 60.

Some dark conspiracy? No. This was a meet-up of the Philly Bitcoin Society at 30th Street Station on Thursday. Announced on Meetup.com, Facebook, and elsewhere, this was a gathering of people excited by one thing: Bitcoin.

Wait. What?

Bitcoin is a Web-based system of monetary exchange. It went live in January 2009. Its inventor's pseudonym is Satoshi Nakamoto, one of the world's most famous fictional people. Is it a person? A group? And where's Satoshi? No one knows.

No central bank, no government to back it up, no shiny metal , Bitcoin runs on the agreement of all parties to use it as currency. Also, there is no coin. The actual currency is a bunch of "0"s and "1"s on your computer and millions of other computers worldwide. The network is what gives it value, and the network is what makes cheating hard.

"I'm really excited about Bitcoin and trying to find out all I can," said Terry McCall, a Philadelphia salvage operator who was at the Thursday meet-up. "I think Bitcoin is the evolution of money."

The guys at the meet-up were animated, ears cocked to learn. Can you get refunds in Bitcoin? Can you do escrow transactions? Where's a good place to go for information? (The Bitcoin Forum bitcointalk.org was suggested, as was the podcast Let's Talk Bitcoin, letstalkbitcoin.com.)

"There's a lot I don't know," said Jason DeLuzio of Fishtown, "but there's someone here who will know, and maybe I'll know something they don't. This is how this world works."

Wharton School students Kyle Powers and Chris Yim are vets of the Bitcoin world. "We have vendors, researchers, even a couple of academics," Powers said. "It's a very open group," Yim said. "We're trying to get integrated into the local community."

One thing all members want to know: Can you make money?

McCall is looking for Bitcoin microdonations to help his business expand. You have Sam Weinrott and his Pirate Printing Co. (see below). And Yim and Powers have a new enterprise rounding the turn.

No joke, this Bitcoin. An estimated $1.5 billion worth of Bitcoin transactions are done daily. The value of a Bitcoin has risen from $20.41 at the end of January to $876.77 as of midday Friday.

After a much-publicized October FBI shutdown of Bitcoin marketplace Silk Road (where, allegedly, people merrily traded in drugs and murder contracts), the currency was the subject of Senate hearings in November.

China said this week it would not let banks speculate in Bitcoin - and overnight, the value fell 30 percent (it had been above $1,200). Speculative trading in China accounted for about 60 percent of Bitcoin transactions in the last two months.

So far, Bitcoin is mostly a speculator's gewgaw. "The Bitcoin market is mostly speculation on its potential," said Steven Keuchel of Philadelphia. "Big companies aren't doing much yet. That would bring more trust to it."

But you can, and a lot of people do, run a business in Bitcoin.

Sam Weinrott of Philadelphia does. He recently opened his T-shirt biz, Pirate Printing Company. "I launched the website on Black Friday, posted on Coinmap, Reddit, the Bitcoin sites, and I'm getting a fair amount of traffic," said Weinrott, whose nonvirtual job is data analyst for WineAccess.com.

"I've sold 33 shirts. The vast majority have been Bitcoin purchases. So I've sold about a half-Bitcoin worth of shirts. I think Bitcoin is awesome."

Some folks think it's shady. The process is, to be precise, pseudonymous. It's double-blind, double-encrypted, and your "name" is a numerical pseudonym that does not lead to any further information.

In light of Silk Road and the recent evaporation of black site Sheepmarket along with a possible $44 million in Bitcoin, aren't people right to worry? Couldn't Bitcoin be used for money-laundering, drug-running, terror?

"Maybe it could," Weinrott said. "But the shadiest currency on the planet is U.S. dollars. A lot of those go to fund al-Qaeda. So?"

In November, Sen. Tom Carper (D., Del.) chaired the Senate hearing on Bitcoin. What does Carper think now?

"I don't know that anyone can say for sure whether virtual currencies are here to stay - or how they'll be used if they do persist," Carper wrote in an e-mail, "but it is clear that the federal government needs to pay attention and apply thoughtful, measured policies in this realm.

"[F]rom what I can see, people want to use this currency today. I want to make sure Congress and federal agencies respond in a way that preserves national security and protects consumers but also promotes and allows technology to thrive."

For Weinrott, virtual currency is here to stay. "It's not so much, 'Is Bitcoin right or wrong?' " he said. "The bottom line: It is, and it won't not be."

jt@phillynews.com

215-854-4406 @jtimpane