Is it an operating system, is it a user-interface? No, it’s a smartphone platform.

Samsung held a splashy event in London today to officially unveil bada, which the South Korean handset-maker is calling “a smartphone platform.” However, the event left people just as confused as they were before. Initially, when it was announced last month, several reporters called it a replacement for its feature-phone technology, then it was explained as a replacement for Symbian’s OS (which Gizmodo rightly or wrongly reiterated today).

The bottom-line is this: developers, carriers, publishers and others in the ecosystem should consider it a new operating system. That’s because Samsung has built an accompanying SDK today, which will act as the blueprint for anything that is built for the platform. In other words, applications built for Java, Android, Symbian, the iPhone, or any other smartphone platform won’t be compatible. Welcome Samsung to the world of more fragmentation.

Specifics about the platform are few, but Samsung is definitely promising everything, but the kitchen sink. In a release, Samsung said bada will provide flash control, web control, motion sensing, fine-tuned vibration control, and face detection. It will also support sensor-based, context-aware applications and use various sensors such as accelerometers, tilt, weather and proximity. The platform will also support all the latest social networking wiz-bang stuff, like device sync, content management and location-based services.

Samsung is calling it an open platform because developers will have access to the SDK and will be able to integrate some of the major phone attributes, like phone calls, messages or contact list info. However, whether it is really open is not clear yet. There’s no promises being made about how companies will take their apps to market, or what the revenue-sharing arrangement will be. Presumably that information will be available soon. Samsung will host a number of “developer days” in Seoul, London and San Francisco. It can’t be too bad. There were a handful of companies on hand at the event sing the platform’s praises, including Twitter, Blockbuster (NYSE: BBI), Capcom, EA Mobile and Gameloft (EPA: GFT).

To be sure, if there’s one thing Samsung has is a massive global marketshare. If they pull this off, bada will be a platform that all developers will clamor for—because they sell millions of devices every quarter. Whether it’s much different than Samsung’s pseudo-smartphone phones that are based on its TouchWiz technology, it’s really not clear. PhoneScoop reported a few more details live from the event: Bada will be based on Samsung’s TouchWiz UI, and bada will be on the majority of its touch phones moving forward. The first handsets should hit the market in the first half of 2010—first in Europe.

Samsung issued a second press release today, too. Oddly, it was about a consumer survey it conducted with 500 people in Italy, France and the UK. Mostly, it sounded like Samsung was trying to justify this massive investment, which could go up against major competitors, like Apple (NSDQ: AAPL), Microsoft (NSDQ: MSFT) and Google (NSDQ: GOOG). The highlight of the survey was that 42 percent of current feature phone users would pay to download applications if they could – and 54 percent of those people would be prepared to pay up to €5 for each application they download.