Diablo – Is the Paragon Gold Find bonus exempt from the cap

Old question already answered, but since the game has seen some changes since, an update seems necessary for the newcomers:

Currently in patch 1.0.7, the hard cap on Magic Find is 625% (300% soft cap + 75% NV stacks + 250% MP 10 on Inferno).

Starting in patch 1.0.8 however, the Magic Find bonus from shrines will be able to exceed the “soft cap” of 300% that players can achieve from a combination of their own gear and their follower’s gear. In patch 1.0.8 we’re also adding a buff to multiplayer games called “Strength in Numbers” which allows for a 10% bonus to Magic Find, Gold Find, and experience per additional player in a multiplayer game, up to a maximum of 30% in a four-player game. The Magic Find and Gold find bonuses of this multiplayer feature can exceed their respective 300% cap as well.

So after patch 1.0.8, if you have 300% Magic Find from your gear and your followers, have 5 stacks of NV (+75% MF), are playing on Inferno at MP10 (+250% MF), have a Fortune Shrine buff active (+25% MF), AND are playing a four player multiplayer game (+30% MF), you can hit the maximum of a 680% bonus to Magic Find. Shiny!

Keep in mind that this cap will be lower for if you aren’t playing on Inferno and/or aren’t using Monster Power level 10, etc.

Source

Nobody outside of Blizzard knows the specific number yet, but the number is at least 100,000,000,000 as that's the max amount you can list an item at in the auction house.

Source: http://us.battle.net/support/en/article/diablo-iii-auction-house-functionality

As with every game, there is a technical limitation, but that depends on how the number is stored. A 32 bit signed integer would put the cap at roughly 2 billion(or 4 billion if unsigned), but since the max bid amount clearly surpasses that, I suspect that they may be storing it as a 64 bit integer, putting the technical cap at 18,446,744,073,709,551,615.

Of course, Blizzard is free to make it lower than that number, and probably have done so.