Yobongo, an iPhone application for serendipitously connecting nearby people in mobile, chatroom-like environments, is launching in private beta Monday.

The previously stealth startup hails from Caleb Elston and David Kasper, both formerly of Justin.tv. The two started working on the application in March of 2010 and left their Justin.tv jobs in October to pursue Yobongo full-time. Their mission is to help people better connect with others in the world around them.

Yobongo, as described by Elston, is a new way of communicating with real people. At launch, the application automatically drops the user in a chat room — based on location — where he or she can start chatting in a group environment with others in the room. Chat room members can also see each other’s avatars at the top of room, and start one-off private conversations with other room participants.

The key difference from applications such as MessageParty is that Yobongo controls who gets placed into what rooms and when. It’s a serendipitous experience engineered by a number of variables that the service uses to determine the makeup of each mobile chat room.

Location does factor into the experience, but the application is more people-centric, says Elston. So, rooms dynamically adjust based on where people are and the flux of a city, but the velocity of users coming in and out of the app and the nature of the individuals (i.e. if they’ve chatted before) also play a role in where users end up.

Prior to today’s private beta launch, Yobongo was being privately tested by a small group of individuals, which means many of Yobongo’s features are unproven.

In a short test, I experienced firsthand just how fast the messaging experience is — in terms of mobile messaging, it’s as real-time as it gets. But because of the restricted nature of the private alpha, I was messaging in the application’s only room. The experience was entertaining and fun, but none of the people or location factors mentioned above played any role in determining how I was placed in the chat room. The private beta will continue to be a controlled test, so the elasticity of the application will still be hard to see in action.

Yobongo is currently self-funded, but Elston and Kasper are said to be in talks with investors. The two believe that as the market for location-based advertising matures, Yobongo will find a way to monetize its service.

Yobongo has fielded interest from thousands of would-be users, but Mashable readers can cut the line. iPhone owners can sign up here to receive priority access to the private beta.

Image courtesy of Flickr, nitot

More About: iphone app, location-based apps, Mobile 2.0, startup, yobongo

The Spark of Genius Series highlights a unique feature of startups and is made possible by Microsoft BizSpark. If you would like to have your startup considered for inclusion, please see the details here.

Name: Pose

Quick Pitch: Pose is an iPhone app that allows users to share photos while they shop.

Genius Idea: If the recent surge of photo-sharing and object-tagging applications, such as Instagram, picplz and Foodspotting, are anything to go by, iPhone owners love to take photos with their phones, and they love sharing them with friends and strangers alike.

Enter Pose, a Santa Monica-based startup that’s attempting to cut out a niche in the photo-sharing crowd with an iPhone app [iTunes link] (coming soon to Android) targeted directly at fashion and shopping enthusiasts. Pose launched in beta last week, having just raised $1.6 million from True Ventures, GRP Partners and Founder Collective, with participation from angel investors (and Path founders) Dave Morin and Shawn Fanning.

Currently, the features are very limited: Users can snap photos of apparel and accessories while they shop, tag them with their prices and the location of the store in which they were found, and then share them with other Pose users, as well as their personal Facebook and Twitter networks. Users can also explore and bookmark the most recent and most popular finds of other users, and peruse those of Pose’s roster of curators, a.k.a “posers” (including, notably, designer Norma Kamali). And that’s about it.

What it’s missing, primarily, is all of the features that make other truly social apps addictive: mainly, the ability to follow others and be followed, to view the activity of one’s personal network in a newsfeed and to add comments in-line. Following would appeal to both tastemakers and the countless number of Internet users who already follow style blogs, whilst commenting would allow users to solicit feedback on their finds from both their personal networks and the Pose community, thus rendering apps like Fashism and Go Try It On obsolete.

Pose could also use a few bonus features to persuade consumers to use it over other photo-sharing apps when shopping, such as photo filters that reflect current trends in fashion photography, or, say, the ability to purchase and/or put on hold items found within the app, a la Lucky at Your Service.

Although it has a long way to go, Pose has an inviting, user-friendly (and thus promising) interface and set of advisors, including Jon Callaghan of True Ventures and Mark Suster of GRP, which is why it’s on our to-watch list.

What do you think of the app? What other features could be added to to make the app more compelling?

Series Supported by Microsoft BizSpark

Microsoft BizSpark

The Spark of Genius Series highlights a unique feature of startups and is made possible by Microsoft BizSpark, a startup program that gives you three-year access to the latest Microsoft development tools, as well as connecting you to a nationwide network of investors and incubators. There are no upfront costs, so if your business is privately owned, less than three years old, and generates less than U.S.$1 million in annual revenue, you can sign up today.

More About: fashion, iphone app, pose, spark-of-genius