Thoduv has released the first DS Emulator for Linux:
DeSmuMe is a great NDS emulator for Windows by Yopyop. Recently he decided to stop the developpement of his program and to release the source. I download it and try to build DeSmuMe on Linux using SDL. Seeing it worked great, I write a small GTK+ interface for this emu. (a bit slower than Windows version, because it’s only written in C++)