Today on PHPKitchen, there's some new comments concerning even more improvements to the PHP Shell package to provide more powerful shell access to developers on the command line.
Luckily for PHPers Jan Kneschke has come to the rescue and implemented PHP Shell in userland PHP, which provides many of the features that come by default in the aforementioned languages' interactive shells. If your PHP is compiled --with-readline support even better, standard up-arrow command history is available, as is the ability to backspace into the code you have written but not yet executed.
Demian also includes another note mentioning an addition PHP Shell's distribution method - it's been made available via PEAR and can be grabbed with "pear install PHP_Shell" from the command line.