I've just receivd my voucher book through for offers at COSTCO which are valid from 23/05/2011 - 12/06/2011.
Although its a "voucher book", you don't need to produce them as the price is automatically reduced at checkout.
I haven't posted all of the deals, just the ones I thought were the best. I've done it under one listing instead of having loads of different COSTCO threads. Hope it helps someone...