This week, Mr. Crowley passed the Twitter handle on to another New Yorker, Chris D'Angelo, whose plan is to use it for his campaign to make dodgeball an Olympic sport. "I am by no means a techie. I'm just a guy who wants to throw red rubber balls at others guys and win medals on behalf of my country," he told Betabeat by email.

"I want to make #dodgeball an #olympic sport. The reason its not already is because people can't decide on one set of rules," he explained on Twitter. "My hope is the website will act as a unifying body so all dodgerballers can get on the same page and we can legitimize dodgeball."

There was no money exchanged in the transaction. "I noticed @dodgeball was sitting idle. So I asked@dens if I could have it. I explained my intentions and he graciously agreed," Mr. D'Angelo said. His benefactor even gave the cause a retweet.

Dens, about fifteen minutes after his 5,000th check-in.

Shortly after 4 p.m. Sunday, foursquare co-founder Dennis Crowley reported his location via his cell phone for the 5,000th time. Betabeat was lucky enough to catch the moment--we'd just wandered in for the foursquare Global Hack Day demos and were approaching the sandy-haired CEO when we heard him proclaim the milestone, keyed in on a white iPhone with a not-so-subtle foursquare sticker on the back. We peeked over his shoulder at the four-digit number. It looked very round.

But not as round as the "0" next to it.

"You have zero mayorships?" Betabeat exclaimed.

Mr. Crowley nodded. "I used to have The Scratcher," he said. "That was a good one." The mayorship of the foursquare office is highly competitive, he and marketing pointwoman Erin Gleason agreed. "I think one of the engineers has it," Ms. Gleason said.

Mr. Crowley's 5,000 check-ins included the 800 or so updates imported from foursquare predecessor Dodgeball, he said. His first check-in was at Bleecker Street Bar in October 2003. He never paid much attention to check-in milestones until he saw foursquare users bragging about theirs on Twitter. Some foursquare superusers have 7,000 check-ins, he said.

Remarkable considering the violent reaction many had when location reporting services were new, a.k.a., "Why would you want your friends to know where you are?"

Mainstream perception was and is still the biggest challenge for foursquare, Mr. Crowley added. "As of all things social media. Why would you ever use Twitter? Why would you be on Facebook?"

Speaking of which, we asked what he thought of the social media giant's retreat from the check-in wars. Facebook recently rolled back its Places feature, which originally resembled foursquare in that it required a check-in. Now Facebook's location data will be attached to status updates, similar to Twitter. "They have their own thing carved out with photos and the news feed," Mr. Crowley said. "We've just continued to own to check-in. We started with it and we stuck with it."

The biggest hurdle for foursquare on the technical side is still GPS, Mr. Crowley said, echoing his chief product officer Alex Rainert. GPS drains mobile battery life, and it's still embarrassingly inaccurate. But those inadequacies are getting better every year, Mr. Crowley said.

Meanwhile, the demos were getting started. We took our leave of the mayorship-less CEO and settled in on the floor.

Dennis Crowley left Google a few years later to being work on Foursquare. Patil stayed at Google, where he worked on building out real-time search, integrating sources like Twitter into the search giants results. Last week Patil announced he was leaving Google to become a platform evangelist at Foursquare. "I used to flatter myself by thinking I knew what people could and would do with this kind of data... I no longer suffer from such delusions. The amazing output we’ve seen from the developer community just reinforces how important having a platform is -- letting people build stuff easily makes rich new experiences possible, all while making foursquare a more compelling product to use."

There is going to be a period of adjustment as Patil moves into a different flavor of real-time data. "Google realtime search has a very different relationship to the space of information sharing than foursquare. Realtime search focuses on searching the world and answering 'fresh'queries. On realtime search, you might track the latest developments from Fukushima, watch people brag about their March Madness bracket, or find confirmation that your city just had a power outage.In contrast, foursquare is much more personal - your location and social connections are at the heart of everything foursquare does. With foursquare, you can see where your friends are, find a great new gluten-free restaurant nearby, or share a recommendation about your favorite coffee shop."

Patil's biggest challenge will be giving developers the right set of incentives to build on top of Foursquare's data, and convincing them there is no risk they will suffer the same fate as folks who invested heavily in the Twitter ecosystem. "When I first started back in 2005, I was encouraged to spend some quality time browsing through the database and wrap my head around all the cool, and often secret, stuff Google was working on. It was so exciting to join a company working on such amazing stuff. I’ve only been at Foursquare a couple of days -- and we don’t have a database, per se -- but It’s definitely deja vu, all over again."