I currently have:
$ rails s => Booting WEBrick => Rails 3.0.9 application starting in development on http://0.0.0.0:3000 => Call with -d to detach =
Like said here, you could change the MAX_URI_LENGTH using this code:
MAX_URI_LENGTH
WEBrick::HTTPRequest.const_set("MAX_URI_LENGTH", 10240)