I've only bought a couple of wheel sets, but they only come close to stated weight when stripped bare. No tape, no skewers, and of course, no cassette, tubes or tires.
I lost about 75-100 grams (3-4 ounces ... nearly 1/4 pound... depending on how you like to think of these things) from the original set by simply using Veloplugs and some cheap and only semi-light aftermarket skewers.
Just a point of reference why the wheels are weighed without that stuff. Same reason frames are weighed pretty much completely stripped down, without anything that can be swapped or changed based on user preference or pocket book.
Last edited by Camilo; 06-14-11 at 12:58 PM.