Yeah, unless you're specifically training to increase your deadlift, do them at the end of your workout.
The reasoning is that by the end of your regular workout, your central nervous system will be very warmed up, as compared to the beginning of your workout when it's not as warmed up.
Personally, I've found that my deadlift poundages don't differ too much from beginning vs. end of workout, but I always feel better doing them when I'm thoroughly warmed up.