I've just finished the intial blockchain download/verify in my BitcoinQt client (17 hours..) and I now see that BitcoinQt is happily eating all of my upstream bandwidth. (About 110kByte/sec on my ADSL line.)
I'm going to be applying bandwidth limits to the app using Waterroof, which should probably work --
But shouldn't there be a built-in method for BitcoinQt to be more polite about its bandwidth consumption?