Unable to install rJava in R 3.0 in Ubuntu 13.04

I ran into the exact same issue. My solution was to install the openjdk-7-* via

sudo apt-get install openjdk-7-*

Followed that with

sudo R CMD javareconf

and I was then able to install rJava in R via install.packages("rJava").

While perhaps not the most elegant solution it appears to have solved my problems with getting rJava to work.

For those getting the error:

error: unable to load shared object '/some/dir/rJava/libs/rJava.so': libjvm.so: 
cannot open shared object file: No such file or directory

I solved the error locating the library in the system and linking them to /usr/lib:

$sudo updatedb
$locate libjvm.so
/usr/lib/debug/usr/lib/jvm/java-7-openjdk-amd64/jre/lib/amd64/server/libjvm.so
/usr/lib/debug/usr/lib/jvm/java-7-openjdk-amd64/jre/lib/amd64/zero/libjvm.so
/usr/lib/jvm/java-7-openjdk-amd64/jre/lib/amd64/jamvm/libjvm.so
/usr/lib/jvm/java-7-openjdk-amd64/jre/lib/amd64/server/libjvm.so
/usr/lib/jvm/java-7-openjdk-amd64/jre/lib/amd64/zero/libjvm.so
$sudo ln -s /usr/lib/jvm/java-7-openjdk-amd64/jre/lib/amd64/server/libjvm.so /usr/lib/ 

Installing rJava from the distribution packages as proposed in this askUbuntu answer also works:

sudo apt-get install r-cran-rjava

NOTE: tried from a Debian system.