Felix Geisendorfer has a quick little sorting example posted today showing on way to sort a multi-dimensional array.

Quick challenge, lets say you have an array and you want to iterate through your products by [the key of each subarray in $products] Product.ordering ASC. Whats the fastest way to do this?

His solution involves using an array_flip call on the extracted information (using Set::extract), ordering it with ksort and pushing the values back into the $product array in the right order.

Check out the comments for more examples including ones that make use of array_multisort.