The F.E.C. has simply been trampled by the Obama campaign Well, that's because they know the way the game is really played: if the FEC were to accuse them, Obama would simply scream "racism!" and everyone would run away in terror.
All of this may be of great importance but the FEC, even if they aggressively investigate the suspect donations, will take months and months to make a decision. If any contributions are then deemed illegal then the Obama campaign will just say "Oh well, we will return the donations or give them to a charity".
Of course all of this will take pace after the General Election has been decided.