From this pointer from PHP Magazine:

From Angsuman: "WordPress has unique plugin architecture. Plugins are simply php files which are included (and executed) before any php pages which renders the content, whether it is your blog page or syndication feed or even administrative functions. The plugins can do anything that is allowed by php code, including trashing your hard-disk to sending your bank account details to a cracker etc. Plugins do not operate under any restrictions. Nor can the product recover from errors generated by any plugin. I really miss here Java's strong security infrastructure."

"Still fine and dandy untill you discover to your horror how a poorly coded plugin can bring down your site in no time. Read "At the mercy of WordPress Plugins; how to fight back".

He talks about how to take back control from some of the more obtuse WordPress plugins - you know the ones - that take control and error out the whole page leaving you with nothing more than a blank page. Unfortunately, debugging these plugins is more of a hassle than it's worth, so his "quick fix" is just to remove the offending plugin. Seems to me that if the error reporting on the PHP install was set to the right level, it might help with some of these problems - but what it really boils down to is a need for some kind of error catching in the WordPress software to catch things that might cause errors such as these.