You can transfer the project/data via a USB or firewire hard drive, or a USB memory Stick for example.
You could also transfer it by burning it to CD or DVD.
It should be the same as copying data onto a medium that can hold data and putting it on another machine.
There is a more complex way of copying data between two machines.
It involves a firewire cable linking the two machines and rebooting one of the mac's in "Target Mode".
However, I would recommend using an external HD or USB stick for transfering small projects. I think it'll be easier.
If you want to know more about "Target Mode" let us know. :-)