Whether you believe we’re living in a post-PC world or not, there’s no denying the overwhelming growth of tablets in the past few years. Just this March, IDC put out figures saying 2010 saw the sale of 18 million tablets, but despite the recent boom, the outfit’s now reporting a 28 percent drop in tablet shipments in Q1 2011, bringing first quarter worldwide shipments to 7.2 million. IDC’s latest report points to “slower consumer demand, overall economic conditions, and supply-chain constraint,” but nonetheless estimates that total tablet sales will reach 53.5 million by year’s end, up from IDC’s original estimate of 50.4 million. Once again, Apple’s come out on top of the slate game, with the iPad 2 leading the market, despite its own dip in shipments. E-readers have apparently also seen a decline in the first quarter, with shipments dipping to 3.3 million units. Despite a slow start to the year, however, IDC’s optimistic about future sales, but you don’t have to take our word for it — full PR awaits you after the break.