The plunder value of buildings for gold is still written in the game data files. (proto.xml) I forget what the property is called, but it's pretty easy to find - it worked the same way as Norse favour gathering. (IE, each building had a set value, and removing x% of that value gained an equal percentage of the total gold value.)
AoM isn't installed on this machine though, and frankly, I'm too lazy to go check. So if anyone else is curious, they can do it.
It wasn't, as I recall, a very high amount. A house yielded something like 20 gold. Keep in mind that cavalry have to do all the damage to that house and destroy it in order to get that 20 gold.
According to Deathshrimp, the cavalry-generate-gold bonus was replaced by the Dwarven Armory, which is in my opinion a little bit more significant.
TheShædøwDåwn
If you're like me, then it's possible you're a clone generated from my stolen DNA. I suggest you turn yourself in for destruction immediately.