Those familiar with Bungie Studios will probably be aware of the long tradition of Pimps at Sea. Some might remember it as being an April fool's joke one year (they announced they were producing a pirate game called Pimps at Sea). It's also been used to refer to games that are currently in development.
Well as you can see (assuming the image hasn't been doctored) people are playing Pimps at Sea (Alpha). Could this be Halo 3, which is due for a public beta of multiplayer in just a few months time? Some people think so.