Scaling difficulty

Something I've noticed in a few games I play (Oblivion, Dragon age and somewhat as well Fable 3) is the concept of scaling difficulty.  This is different from choosing what the level of difficulty is at the start of the game.  What this entails is, as the game progresses and your characters increase in level, power and skills, the enemies around you scale up with you.  What this means in practical terms is that your characters never tend to be too overpowered for an area.  The enemies will scale up in terms of equipment, damage, armor etc.  This makes it so that your always being challenged by certain groups of enemies.  I personally find this to be somewhat of an annoying mechanic, as it tends to make it so after spending time finding new equipment, leveling and doing things of that nature, I walk into the next room and the guardsman are now wielding +5 swords of player slaying.  This is a mechanic that I have personally not seen that much in games except for the few I mentioned, so if anyone knows of any others they have seen, feel free to let me know.