Invoking R from PHP/Mysql environment

We have a setup in which we use PHP (with Geeklog as a CMS) as a front end
to MySQL. We plan to use R for offering user driven and automated
statistical analysis of some of the data we obtain. We'll be using the R 
interface
to the MySQL database from omegahat (www.omegahat.org) for getting
the data out of the database, but we were wondering if somebody tackled
the problem of how to integrate R nicely with PHP.

Specifically, we know how to get R to run as a system command from PHP, 
but
ideally we'd like to call R as a PHP function. If somebody did this we'd 
like
to have some pointers as to how they did it If not, we'll probably do it 
ourselves
and post the results

We have a setup in which we use PHP (with Geeklog as a CMS) as a
front end to MySQL. We plan to use R for offering user driven and
automated statistical analysis of some of the data we obtain. We'll
be using the R interface to the MySQL database from omegahat
(www.omegahat.org) for getting the data out of the database, but we
were wondering if somebody tackled the problem of how to integrate R
nicely with PHP.