Currently, the binary is in a gratis-free form. This is a result of the project currently being an alpha release and the binary is simply something for people to test and preview. That's really all anyone can do with the state that the game is at.
As far as the open source nature, yes, the source code will always be distributable and able to be applied to any project. This is because eventually this project will split into two forms: 1) the engine, 2) the actual game. As development stands, the current alpha version is essentially the engine. Eventually, this project will fork and the actual "game" will simply be cruft sitting on top of the engine, while the engine will remain open source.
However, the cruft on top of the game will not be open source. The cruft on top will take the form of data (mostly), some glue code, and other miscellaneous code that is not essential to the engine and only particular to the game.
As the project forks, the nature of what is open source and what is closed source will become clearer. Right now, there is only one page for both things (since it is early in development), so the distinction isn't clear cut at the moment. Currently, all source that has been put into version control is open.
When the project is mature and in a "finished state", I will release a demo version of the game and a fuller version that includes everything for a negligible fee (about the price of a cheap iPhone app). And, because of the open/closed source distinction is conflated with gratis/fee, baldly saying something is 'open source' (without qualifying what is meant) to many people implies categorically that it is or will be free of charge or fee.
So, I'm reinstating the Shareware designation.
-Sean Brown, Dec 23rd 2010, 1:12pm