I confess that I have only a very surface comprehension of this concept. The Wikipedia entry is pretty interesting, although I'm not positive they're using the term in exactly the same way we do.
Starting with work in the Neo-Piagetian tradition,[38][39] theorists have argued that the growth of working-memory capacity is a major driving force of cognitive development. This hypothesis has received substantial empirical support from studies showing that the capacity of working memory is a strong predictor of cognitive abilities in childhood.[40] Particularly strong evidence for a role of working memory for development comes from a longitudinal study showing that working-memory capacity at one age predicts reasoning ability at a later age [41] Studies in the Neo-Piagetian tradition have added to this picture by analyzing the complexity of cognitive tasks in terms of the number of items or relations that have to be considered simultaneously for a solution. Across a broad range of tasks, children manage task versions of the same level of complexity at about the same age, consistent with the view that working memory capacity limits the complexity they can handle at a given age.
There is now extensive evidence that working memory is linked to key learning outcomes in literacy and numeracy.[93] A longitudinal study confirmed that a child's working memory at 5 years old is a better predictor of academic success than IQ.[94]
I don't know how controversial any of this is or anything. I know that DD's excellent WM seems to give her an advantage over and beyond the gifted stuff-for instance, she has no difficulty with math facts or spelling, which seem to be relatively common stumbling blocks even among the highly intelligent kids here. It was one of the first things we noticed about her as a baby--it set her apart at an early age. Interestingly, though, there is one memory-related thing she is not so good at, and that's remembering and following through on a long string of verbal directions. She can parrot back a long quote, but something about "Listen to this AND GO DO this" must be different. (I don't think this is just her being obstinate.)
