Thermalnoise also asked how much your savings of gold fluctuates, and for most people it apparently stays pretty much the same, or generally increases (probably as they run professions, do quests, or sell off drops and pay repairs). I'd imagine Blizzard is keeping a pretty close eye on just how our gold moves around, and that "steadily increase" is what they'd want all of our money to do, just to keep the game's economy moving around.
In fact, though I'm probably repeating myself here, it'd be nice to have them give us some insight on just what's happening with the ingame economy. We've gotten a few hints at what sells and doesn't on the realms, but it would be interesting to see some official numbers about the average amount of money that players have and keep at the various levels of the game. and exactly where it all goes when we spend it.