Very short summary: The commercial pop piece "Do It" by Tim "Timbaland" Mosley for Nelly Furtado supposedly has its origins in the tracker module "Acidjazzed Evening" by the Finnish C64/Amiga demoscener Janne "Tempest" Suni. See Wikipedia for a more detailed summary. Or perhaps this YouTube video if you just want to hear the similarities between all the related songs.
Note: This is just a list of links somehow related to the fuss. Some information presented as factual may actually be speculation or just plain wrong (even if repeated in multiple sources).
The news about the new "Beaterator feat. Timbaland" game for PSP has revived the discussion.