Last week, I received an email from someone who told me how the Suhosin patch had created problems for their team, and suggested that I write about it here. I thought this was a great idea, for a number of reasons. Particularly, Suhosin is one of those PHP patches that alters the way PHP operates in a fundamental fashion, yet also is installed by default in many places (for example, Ubuntu compiles this patch in by default on their installation).
He talks about some of the features it includes - disabling eval, not allowing for remote includes, makes it possible to modify the memory limit per script and allows you to set limits on the length of REQUEST arrays. He notes that, while the Suhosin patch is a good thing and can make a real difference in your application, it's by no means a requirement to creating a secure application (and shouldn't be used as a replacement for such).
There's also an interesting comment from Stefan Esser himself on the comments Brandon made in the post.