As of August 14, 2007, no company was certified by the EPA to convert cars to run on ethanol in the United States. I contacted the EPA and asked how many companies applied. The EPA only says there is "a number" of applications. In a recent bulletin, the Depart of Energy says there are "a few" companies seeking certification. Go below the fold to see a correction to this article.
[Source: DOE] Update: The first version of this article listed companies that I mistakenly believed to be ones listed by the DOE as passing OBD certification and were seeking to be certified for ethanol conversion. Those companies were actually the 14 current certified flex fuel converters for other types of fuels. I apologize for the confusion. I would like to thank stewie81 for noting this mistake in comments. I am still seeking to get a list or number of companies trying to become certified to convert cars to run on ethanol.