You can download the emulator here.
Recent changes include:
- Partial Expansion Module (XM) support
- Support for cartridges with sizes greater than 144k
- Additional bank switching modes and cartridge types
- Reworked cartridge header detection
- Display enhancements (GX+VI, 16:9 correction, 240p, Full widescreen, bilinear toggle)
- Hierarchical file navigation support
- USB and SMB (Network support) for loading ROMs
- Reworked menu system
- Various bug fixes (Kangaroo and Holey issues, audio improvements, etc.)
- Support for launching via WiiFlow (and returning)
For status updates, known issues, or to provide feedback please visit the Wii7800 forum thread.