DarkFader has released a fake DS ROM that claims to be a Hentai viewer or ROM loader but is in actual fact a program that will flash part of your firmware rendering your DS useless. It is apparently possible to fix the DS if you have FlashMe but otherwise you will be left with a brick. UPDATE: To fix if you have FlashMe hold A+B+SELECT+START when switching on the DS, you can then run the original FlashMe updater to restore the DS. There are also reports that it will erase G6, M3, gbamp and SuperCard firmware as well as deleting anything found on the CompactFlash card in the gbamp.
The file was originally released as taihen.zip (.nds size 548,673 bytes) which is an Hentai viewer and then as r0mloader.zip (.nds size 151,361 bytes) which claims to be a ROM loader. At the moment there is no way to be absolutely sure if a ROM is legit so please be VERY careful before trying any new homebrew.