I have written a code to plot results from MultiNest with Python's matplotlib, which might be of interest to CosmoMC users:
You can easily calculate and plot posteriors, profile likelihoods, best-fit points, posterior means, amongst other statistical quantities, in one or two dimensions. To download the code, please see superpy. The plotting routines are in the SuperPlot directory. For instructions, please see wiki. Please don't hesitate to ask me for help if you have a problem.
Best,
Andrew.