I tried out the Pixy XSS and SQLI Scanner (http://pixybox.seclab.tuwien.ac.at/pixy/index.php) on a few simple PEAR files. On the first, I got a java exception, on the second it was unable to resolve the simplest of includes (no ability to resolve include_path). In short, the thing is useless for anything written using PEAR. Fun!
The Pixy XSS and SQLI Scanner is made to find SQL and XSS injection issues in scripts. It runs as a Java application and scans PHP4 source code to try to find problems. For more information on the scanner or to try it out for yourself, check out the project's homepage for documentation and downloads.