Recently JRI was made part of rJava, as by www.rforge.net/JRI "so if you simply want to use JRI, install rJava binary and your'e all set!"
That said, where is the documentation? "http://cran.r-project.org/web/packages/rJava/rJava.pdf" doesn't mention JRI related methods. I googled for it without luck.
Is the project dead? Is anyone using it and can s/he comment? Are there any better alternatives?
Most of the links on the glorious http://www.omegahat.org/contents.html are dead as well.