nesDS, the open source NES emulator currently being maintained by huiminghao, has been updated once again to 0.47a. See the change log for what's new, and join the on-going discussion linked below for more information about this project.
QUOTE(Change Log 03/30/11)
sound enhanced. volume x2.
Famicom Disk System support. (Savestates not supported. Rewind and fast-forward is safe for use)
Note: For FDS, use R+UP=disk A, R+LEFT=disk B, R+DOWN=disk C, and R+RIGHT=disk D.