I've been farming act 1 and act 2 inferno over 1 month now and noticed that the gold drop in act 2 compared to act 1 is lower by 66% to 75%. This is also the feedback that I got from the guys at the office who play the game and friends that I farm with in parties.
Been upgrading gear with more or less GF and doing runs with and without 5 stacks of NV on both acts just to see if this is what affects the drop rate. But I came to the conclusion that any of those variables are not the cause for low gold drop in act 2 inferno. The percentage of gold drop for act 2 is still somewhere 66%+ lower than act 1.
This is only an analysis and I mention this as farming in act 2 can take a toll on the gear (unavoidable deaths from some elites packs using mid to high end gear on a Ranged char). For me and my friends is really frustrating sometimes that after 3-4 hours of farming in act 2, we are left with somewhere around 100k to 150k gold after repairs(Max number of deaths = 5!!!). Usually act 1 with 1 or 2 deaths within the same timeframe of farming we remain with 400k+ gold. These latest numbers are an average of multiple runs with about ~150 GF on both act 1 and 2.
Please comment if you are getting the same results with the gold drop in these acts. I personally don't farm much in act 3 but the few runs I did there, I noticed that the numbers are a little better there. Please feel free to add any analysis on act 3 and 4 on gold drop aswell, if you feel that is the case.