I'd be very interested to hear how this goes for you and what you find (particulary cost, efficiency and problems with sofware functioning in something like that).
Perhaps I'm a bit old school, but I think database replication is best left to the database products, and with a hardware load balancer for a pool of apache servers, you have a perfectly scaleable and standard system. When you start doing things like this, I start to wonder how much impact a distributed file system would have on database performance.
Also, the 'linuxDirector' server and backup director server in their HA config are functionally equivalent to a hardware load balancer (used Foundry ServerIron XL and Cisco Local Director can be had on ebay for under $1,000) which is dedicated to that single task with no moving parts. Given that you already have Oracle, you likely have lots of expensive hardware, and you may find that your University already has load-balancing hardware that you can use.
I've always had a keen interest in finding solid, simple HA solutions for web applications and would really appreciate you sharing your experience in the endeavor.