Recently discovered this command line utility for checking for leaks in C and Objective-C programs. It also works on projects built with XCode (iPhone, etc.).
To use, simply download the tar and extract it into a folder. I made a symbolic link from my home directory to this folder for ease of use.
To scan for leaks in an iPhone project built with XCode, using the command line, change to the directory that contains your XCode project and do:
assuming ~/checker-0.142 is a symbolic link to your installed path for the tool.
If any leaks are found, you will see an error message on the command line letting you know how to view the report using "scan-view". Once run, you will be redirected to your browser with a URL pointing to your localhost on port 8181 (not sure if this port is dynamic).
The author warns that false positives are possible so take these reports with a grain of salt. At least they may point you to the right line of code to start inspecting things closer.