A long sought-after features of JfreeChart is the support for real 3d charts by a dedicated 3d->2d conversion engine. A first announcement dates back in 2007 (see http://www.jroller.com/dgilbert/entry/a_glimpse_of_jfreechart_3d and http://www.jfree.org/phpBB2/viewtopic.php?t=21915\).
Nothing has been published so far.
I have started to work on that topic. Here is a first set of classes.