I heard the story on NPR that there are significant differences in the demographics of the two conventions.  One that stood out is that 36 delegates to the Republican convention are black, or less than 2%.  

Here's the story I found from a local Chicago ABC affiliate.  

The Republican National Committee is not releasing any official numbers about the demographics of its delegates, but some staff called from the Joint Economic Center for Information say there are about 1,900 delegates, and 36 of them are African American. That's about 1.5 percent. In 2004, at the Republican convention, seven percent were African American.
At the Democratic convention in Denver this year, 44 percent of the delegates were minorities, including all minorities, not just African Americans. And also a majority of those delegates were women.
At the RNC, the men outnumber the women 2-1 on the delegate floor. The average age for both parties' convention delegates is 54.

Yesterday I heard the interview with Thomas Franks about his new book, The Wrecking Crew: How Conservatives Rule.  He is the author of "Kansas" of a couple years ago.  You can hear the whole interview on podcast at Fresh Air with Terry Gross.  He lays out how the Bush admin. has systematicially dismantled government and turned over more functions than ever to private business, who has now figured out how to make a big profit on it.