The US has finally imposed sanctions on the Gbagbo government in Ivory Coast.  This won’t accomplish anything.  Take the response of the Ivorian Interior Minister (via allAfrica.com):

A top adviser to Gbagbo has said the sanctions are “a threat” to Cote d’Ivoire and his interior minister told RFI the measures “make me smile.”

Of course they do – this is just what Gbagbo and his people wanted – now they have evidence of “outside interference” in Ivorian affairs which they can mobilize as a rallying point for patriotism – and in so doing, relegitimize Gbagbo as the defender of the country.
While it is interesting that Deputy Assistant Secretary for African Affairs William Fitzgerald is leaving military intervention on the table as an option, note that he has effectively ruled out US military engagement:

He said it was unlikely that U.S. troops would participate if that option was taken and that it was more likely to be an African force.

This is not a threat.  ECOMOG, the armed monitoring group of ECOWAS (the Economic Community of West African States), was able to retake Freetown in Sierra Leone during that civil war, but could do little else.  And that was a relatively successful intervention in a much smaller country.  This is like threatening to hit someone, but only with a nerf bat – annoying, but not really terrifying.
This has gone too far down the road now – someone is going to have to commit real troops to this conflict, and quickly – the UN peacekeepers won’t be able to hold the line much longer.