The DAO is a group of people putting together their money to manage it and make more. This is done through proposals and members voting on passing them.
Based on the proposals that are accepted, the DAO can be anything really: a hedge fund, VC fund, lottery-system, gambling pot, etc.
What it becomes is still undefined and we can only see with time based on proposals and how the members vote. That alone is really interesting and exciting to me: will members actually make intelligent decisions or will it crash and burn?
The DAO also shows the power of the underlying crypto, Ethereum, on which this was built.