Research firm IDC today announced its preliminary estimates of worldwide tablet shipments for the first quarter of 2013, finding that Apple's share of the market continues to slide as competitors begin to gain footholds in the market, although the firm notes that Apple did exceed expectations. Apple held a 39.6% share of the market for quarter, compared to 43.6% in the previous quarter and a 58.2% share in the year-ago quarter. Worldwide Tablet Shipments in 1Q13 in Millions of Units (Source: IDC)Apple outperformed IDC's most recent projections for the quarter, shipping 19.5 million units compared to a for
