Hi Jonathan,
if you want to use pd in a commercial application, and particularly if you want to use it  as the basis for an iphone application, then you cannot include anything that is licensed under the GPL license.  In vanilla PD, this means that you have to remove any expr objects.

The rest of pd is licensed under the 'standard improved BSD license, which if freer, and allows you to use pd for commercial applications without revealing the source code, too.