In the past, our only solution was to drastically reduce the gold dropped by legacy content across the board (e.g., Magtheridon, much of Karazhan, etc.). In Mists, we have a new system in place that normalizes gold yield based on the number of players involved in the kill. If a Black Temple enemy drops 100 gold today on live, and you kill it with a 25-player raid group in Mists, it'll also drop 100 gold and each player will get 4 gold. If you solo Black Temple, that enemy will also give you 4 gold. If you do it with 4 friends, it'll drop 20 gold and each of you will get 4.
In other words, the gold obtained from killing raid or dungeon creatures no longer depends upon how many people you bring, or do not bring, with you. This system does not apply to anything in the outdoor world.
This is going to come as a disappointment to many people who like to farm old content not simply for the gear and items that drop, but also for the gold hit they receive from bosses. My husband particularly enjoys a weekly wander around Serpentshrine Cavern, where (I believe) the easier bosses he can happily solo reward a 250g payout. The concept of normalising gold across the board is one I have to say I welcome, if only because it encourages people out of older content and to the newer stuff to make their living.
Gold generation really should not be a problem come Pandaria anyway, with no limit on daily questing and over 40 dailies available on any given day. Needless to say, I am sure the more zealous gold generators will consider this not only a nerf, but Blizzard 'removing fun' from older content. I'd like to think it could be the first step to preparing older raids for LFR accessibility...