6 Months and Growing!
The last month has brought many subtle changes. So subtle that we've overlooked them before making this post. He's become more aware that people aren't disappearing, and are simply going around corners (Which means he'll look at a door until mommy comes back. He's become very good at associate certain sounds with certain stimuli, which means he'll put falling asleep on hold if he hears mommy or daddy come through the front door - no matter how sleepy he is at the time.
He has become much better about keeping his arms in front of him during tummy time, which he still hates. To be honest, we've become better about initiating tummy time :).
Walking drills are going much better! He's taking his walking and pushing it forward before taking a couple of steps! Of course he's still being supported during the process, but he's learning to stabilize his weight each time we initiate the drill.