I've heard recently here that Litecoin became more GPU-friendly. When did this happen, and what were the changes to the protocol to accommodate that change. Also, is there any reason for the change provided by the project developers?
Nothing in the litecoin protocol changed, only a tool to mine litecoins using GPU was independently developed: the Reaper and caused difficulty to improve to make CPU mining much less efficient (compared to electricity price). Still, the rise of diffculty is not so dramatic as was the case for bitcoin and scrypt algorithm has proved its worth. CPUs can still mine 1-3 LTC/day at the moment.