Here’s the design they picked:

Kierantimberlake Architects

Key quote from the article:

The project as a whole, however, is a fascinating study in how architecture can be used as a form of camouflage. The building is set in a spiraling pattern of two small meadows and a pond that have as much to do with defensive fortification as with pastoral serenity: an eye-opening expression of the irresolvable tensions involved in trying to design an emblem of American values when you know it may become the next terrorist target.

Over at the Embassy’s official page they have a few more renderings, including this one that’s much more spikey than the last:

Kierantimberlake Architects