A handful of US and European developers have been working in stealth mode on game engines and frameworks with low barriers of entry: inexpensive or free, browser based, pre-built components and code. Now that these products are beginning to come into view it’s notable that most are using social media as an integral part of their business model and banking on users to build a good deal of the content.

Arguably the most anticipated of the web-bred MMOs is San Diego based Areae, in part becuase of founder Raph Koster’s street cred in the MMOG world. They’ve been laboring for months under a level of secrecy Apple would be proud, but finally tipped their hand at the TechCrunch Conference where they announced and demoed Metaplace, “…a next-generation virtual worlds platform designed to work the way the Web does. Instead of giant custom clients and huge downloads, Metaplace lets you play the same game on any platform that reads our open client standard. We supply a suite of tools so you can make worlds, and we host servers for you so that anyone can connect and play.”

“You should be able to stage up a massively multiplayer world with basic chat and a map you can build on in less than five minutes. It’s that easy. Inherit a stylesheet — puzzle game, or shooter, or chat world — and off you go! Building maps and places is as easy as pasting in links from the Web, and dragging and dropping the pictures into your world.

“What’s more, you can link your world to someone else’s world. Put a doorway in your virtual apartment that leads to Pirate Vs Ninja-land! Stick your world in a widget on your Facebook or MySpace profile. Mail it to a friend and they can log in with one click.” You can read more in Wagner James Au’s story about MetaPlace on GigaOm.

Alright, get me some of that! I’ll report more once I spend some time with the Alpha release. But meantime where there’s smoke there’s fire, and when you look around you find that MMOG pioneer Koster isn’t the only one out in front in this space. In coming weeks/months look for Alpha and Beta releases of social gaming products from these companies:

• Combining Flash with community features, Kongregate seeks to “create the leading online hub for players and game developers to meet up, play games, and operate together as a community.” Similar to Manifesto Games which publishes and sells independent product, a portion of revenues - in this case from advertising - evidently goes to the developers supporting the site

• Bay Area developer Roblox has an Alpha release of a web service that promises a “Free virtual world-building game with avatar chat, 3D environments and physics” and allows users to build MMOG environments using Lego-like building blocks of graphics and code. Though the business model and positioning of Roblox is not entirely clear, it looks like their high quality physics engine is a key differentiator that gives them the potential to productize a version for the formal education market.

• Another new MMOG called Travian from Germany is a browser based game where you choose between three tribes in Romans, Gauls and Teutons, build and improve your village and I think eventually gain enough people and assets to raid other villages (I’m still building my village so what comes next isn’t that clear). Although there’s a Java chat client on the site, because it’s located a page away it doesn’t feel very well integrated with the game. This is an example of what *not* to do to foster social interaction, IMHO, though it may just be an early stage concession to getting the v1.o product out the door.

• What do you do when you mix social networking, avatars, and casual games? You get Flowplay, a “next generation social entertainment platform for casual games.” Not much on their site yet but Gamezebo has posted this interview with CEO Derrick Morton that sheds some light.

• New entrant Conduit Labs asks “Why can’t we do more together online? In the real world we get together to dance, play hoops, even skydive out of planes. Online we can add people to buddy lists, but there are few options when we actually want to create, compete, and play together.” Again, there’s not a lot on their website so try again next month or visit Conduit Lab’s blog for more info.

• InstantAction, born from the merger of Garage Games with Barry Diller’s InterActive Corporation. Though what they’re planning is a little vague, the partners claim to be “Introducing new technology which allows graphically rich, networked games to run in popular web browsers with no download installation, InstantAction will enable easy access to single player and multi player games with core-oriented mechanics and high-end visuals.” They have also announced a game development fund aimed at “fostering a new generation of game development for the internet.”