Thought number 1: Is the print version of Wikipedia going to have things in it like "List of famous gay, lesbian, and bisexual people" in it? That should distinguish us from the Columbia Encyclopedia and the Britannica, all right! Leaving Wikipedia subject to attack only by the clan Wallechinsky... (and, conceivably, disgruntled members of the list who object to their inclusion).
Thought number 2: regardless of the legal defensibility of the use of some other encyclopedia's list of articles as a guideline for shaping Wikipedia's, it strikes me as being intellectually lazy and a bit dishonest. If we claim to be producing an encyclopedia, and do not have any other way of knowing what should be in it other than to compare its contents with some other encyclopedia, we're certainly leeching off of someone else's work, regardless of whether or not they can conduct a successful lawsuit over the matter.