Reduce verbosity of log files

Whenever there's a ruby error (even just a syntax error) in my
controller (or anywhere else for that matter) my development.log gets
filled with a massive ActiveXXX stack trace where the first 2 or 3
lines contain all the info I need. Where is that configurable?

Thanks...The reason for the separate posts is because it's useful to
keep different questions separate - it's easier for people who might
want to answer.