yes, this is possible.
You could use message queues or shared memory, both are supported by PHP (only on *nix systems though).
you could even use shared memory in php and access that same piece of memory from another program.
Details here:
http://us2.php.net/manual/en/ref.sem.php
Tutorial:
http://www.onlamp.com/pub/a/php/2004...ed_memory.html
and to respond to this: "Since PHP can not do this, it's limiting a lot of potential speed ups in efficiency. PHP could get nowhere near the speed of Python+CherryPy in some situations."
This may be true, but shared memory doesn't scale very well. For high performance, it's best to use something like memcached (slashdot and livejournals use it to scale their sites to many different servers).
Link:
http://www.danga.com/memcached/