Shouldn't verbose logging go somewhere other than @rack.errors? This pollutes STDERR with debug info that'd be better-served in STDOUT; on Apache/Passenger/Rails 3.1, these all go to the error_log.
I have similar issue when using capybara-webkit.
I don't think it should go to either STDERR nor to STDOUT.
Maybe it should just go to a log or something?
On the other hand the verbose is supposed to be "chatty" and it usually goes to STDERR/OUT.
Logging goes to rack.logger when defined now as of 805001b