A lot of sites have been doing a poor job covering the Ron Paul newsletters. It seems that, not surprisingly, the Libertarians have been the best at explaining what's been happening. Conor Friedersdorf does a good job at explaining what happened. He draws upon this 2008 Reason article that seemed to get to the bottom of the authorship issue. And this post over at Bleeding Heart Libertarians gives even more of a background on the politics within the Libertarian party at the time.
For those of you that want the brief overview: It seems that Ron Paul didn't write the newsletters, but that they were overseen by his friend and partner in the venture, Lew Rockwell. This was part of a larger movement within the Libertarians, lead by Rockwell and others, to try to get supporters by appealing to racist and extremist views.