Over Labor Day, my friend and I noted that the crowds did seem a bit lighter than previous Labor Day weekends. And we stayed at the Renaissance on a stay three, get the third night free promo that made our effective rate $75 at the best Marriott product near the Strip.
I did notice Orleans going down to $60 or so over Labor Day weekend, and the LV Hilton had some $75 rates available until a week or so before the weekend, but the big boys appeared to still be able to fill up at premium rates and didn't discount much.
The next big test might be CES - if the rates drop more than 10% I'd say Vegas was definitely feeling a recession.