In a recent post to his site Christian Weiske shares some of the first steps being made toward an installer he's made that could be used for installing PHP applications of just about any type.
Half a year after I collected requirements for a generic PHP application installer, Kore already implemented the first bits of it for the Arbit installer, which is supposed to be generic enough for other PHP applications, too. He also held a talk at the PHP Unconference in Hamburg, collecting more requirements for it. There is already some code in arbit's svn repository which at least generates a .phar file that checks your application requirements and collects configuration options.
An example of a simple build is included that will create the Arbit installer package that, when executed, will give a basic configuration screen. They suggest making .phar files executable by the web server too (interpreted by PHP) just to make things simpler.