WoW Insider reported that the presumed gold cap limit, the sum of 214,748 gold, 36 silver and 48 copper, was achieved last week by two of the top clan leaders:

Dorgabas on the official forums and meth on MMO-Champion's forums both reported the discovery today, each with a screenshot to provide veracity to their claims. You can check them out by clicking here. The shots are of two different players, one of whom is on a German-speaking server. In the shot you can read his conversation with a GM, which supposedly translates to him asking the GM about the limit and the GM scratching his head in response.

Apparently you can be too rich for Blizzard. Not that any of us will see a fraction of that!