hi
as the Arduino eagle files aren't currently released, and there are some who would probably like to have them, I have drawn them up and posted them
here. There is just a schematic there now, but it is 100% compatible with the current Arduino hardware, namely the Diecimila. If you design a PCB variant, post here or message me and I'll link to it. I'll release a through-hole PCB version when I get a chance.
Also, as there are many questions without answers about who can use the "Arduino" name, I invented a name that anyone is free to use... Freeduino. After you finish reading this sentence you are hereby granted an unofficial license to make things called Freeduino. You have to read the whole sentence though. If you have read this far you are already a licensed Freeduino maker! Congratulations.

I drew the schematics from the Arduino Reference design, which is released under CC 2.5. You can use this design for any use you like, as long as you maintain the original CC 2.5 license conditions that the design came from.
Daniel