I have the same issue:
Sins is updated to 1.05
I d/l'ed the & deadly sins mod to:
C:\Documents and Settings\Administrator\Application Data\Ironclad Games\Sins of a Solar Empire\Mods
The "Mods" folder wasnt there. So I simply created it.
Inside the "Mods" folder is another folder named "7sins" which contains several folders (Gameinfo, Mesh, particle, etc.)
When I boot up & go to options > mods
nothings there 
There's an option to check the mods directory path in the ingame menu & it's the pointing to the correct directory path
(C:\Documents and Settings\Administrator\Application Data\Ironclad Games\Sins of a Solar Empire\Mods)
is there a piece to the puzzle that I'm missing here?
Any help would be really appreciaterd & Thanks in advance 