Just the standard Apple VGA adapter will work for direct connect to a digital projector.
I am trying to figure out a wireless method of connecting. I think Apple TV will do the trick, but I live in Korea, so my access to Apple accessories are a bit complicated and expensive.
There are other threads on this forum that talk about various projection capabilities. You would think, with all of the interest in projecting, that Apple would come out with a clear cut method/explanation.