[citation][nom]hokkdawg[/nom]Question - is Apple really stealing market share, or have they simply provided a product that has expanded the total market size? Or, rephrased - are Sony and Nintendo really selling less product, or has the market just expanded and caused their percentages to decrease?[/citation]
Market share and sales numbers are 2 different thing. The market share compares the sales of a product to those of other products. It's not compared to the numbers of units sold in a different period of time.
So, while Apple probably augmented the total number of games sold, we can't assume that. Would people have bought the same game on a different platform? We can't assume that either. What we do know is that Apple sold more games than last year, so they do have a higher market share, regardless of the sales of Sony and Nintendo.