Right, the difficulty adjustment is trying to keep it so the network as a whole generates an average of 6 blocks per hour.  The time for your block to mature will always be around 20 hours.

The recent adjustment put us back to close to 6 blocks per hour again.

There's a site where you can see the time between blocks, and since block 68545, it's been more like 10 minutes per block:
http://nullvoid.org/bitcoin/statistix.php