nesDS, the open source NES emulator currently being maintained by huiminghao, has been updated to 0.45b. 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 03/25/11)
The memory region of "NES" is relocated from 0x23f0000 to 0x23ec000, as advised by avenir. Now the nesDS on my DS can return to the homebrew menu.
A software for sprite-scaling is added. Select 'Per-scanline' to active it.
Mid-frame BG pal refresh is supported. Some games like 'Wizards Warriors' work fine now.