from michniewski:

Tantric and I (michniewski) are proud to present a new version of Snes9xGX. This release is especially significant because the core has been updated to Snes9x 1.51, which should make many games work, and it fixed many annoying issues. You can see the full changelog here: http://snes9x.ipherswipsite.com/ Special thanks to the snes9x team.

The menu layout has changed since 004, and many items have been moved around. Hopefully this layout makes more sense.
Preferences are saved in an xml file so they can be edited easily. You can also load and save over SMB on the wii now - and thanks to the preferences, all that you need to do is set up a SMB share, and update the settings in the Snes9xGX xml preferences file.

Superscope, Mouse, and Justifier support has been added in this release, controllable with the GC controller, classic controller, or wiimote.

Cheats have been enabled. Put .cht files with the same filename as your ROM in the snes9x/cheats folder and enable/disable them via the menu.

Thanks to libdi, you should be able to load DVDs in wii mode. Make sure you have DVDX installed. See http://hackmii.com/ for more info.

Finally, you can now choose between 3 render modes: Filtered, Unfiltered, and Original. Original and Unfiltered offer sharper graphics - modelled to give an output as close to a SNES as possible. Using unfiltered or original modes is recommended. (original only available on non-component video cable setups)

See the readme for full changelog and more information.

Source
Download the source code from http://code.google.com/p/snes9x-gx/

Known Issues
- The mouse can be a little funky. The cursor doesn't update correctly.

Installation
Wii:
Copy over the contents of the apps/Snes9xGX/ directory over to your SD card (to run it from the Homebrew Channel)
GC:
Load the gc dol in the executables directory.