We all know the iPad is king of tablets, but it would appear that Apple has extended its lead in the slate market shipping approximately 70 percent of all tablets in the second quarter of this year. Unfortunately for Apple, Google’s recently released Nexus 7 tablet isn’t included in these numbers as it only started shipping after the April-June quarter was over. Up from a 58 percent market share in the first quarter, Apple now holds 69.6 percent of the market, according to research firm IHS iSuppli.