While looking into setting up a logging framework within our code, I came across an article that discusses logging the FireBug console from within PHP. Coupling this with the PEAR::Log documentation on redirecting non-fatal PHP errors, I now see PHP errors in my FireBug console, rather than in my pages.

The first article also mentions FirePHP, which consists of both a PEAR extension for PHP, and a FireBug extension for your browser. This combination allows for much more structured debugging information to roll up to the browser, but at this point it seems to still be somewhat beta.