The Yarn Harlot was going on about blocking last week, and I agree completely.
So completely that I thought I'd offer up a little evidence in support. I finished knitting my Moyen Age last night and wove all the ends in today, but it hasn't yet been washed or blocked.
I took these two pictures earlier. See how in the first one the stitches are nice and even?
And how in the second there are little uneven places?
Same yarn (well, the second picture is a different skein, which is why it has a little more variegation), same needles, same piece of knitting--the difference?
I washed the lower half of the sweater to make sure my gauge was right before I knit the bust.
That, ladies and gentlemen, is the power of blocking.