I read an excellent essay by Robert Silverberg in the December 2007 edition of Asimov's Science Fiction Magazine: "Reflections: Rereading Heinlein", which addresses issues I tried to cover in my 'from author's mind to reader's mind' blog from earlier in the month. Silverberg says: "Instead of pausing to explain, he simply thrust character and reader alike into those worlds and let communication happen through experience. He didn’t need to tell us how his future societies worked or what their gadgets did. We saw the gadgets functioning; we saw the societies operating at their normal daily levels."
So, authors, build those worlds, but be sure to SHOW us how they work!