Diablo III Paragon System Revealed, New Auction House Changes Detailed
This new system will also be imposing a 300% cap on Magic and Gold Find before the Nephalem Valor buff, which means that reaching the 100th Paragon level will cap your Magic and Gold Find, essentially rendering any additional gear to provide those stats obsolete. Just don't expect to get to that level cap too quickly.
The first Paragon level should take about as long as it took most players to get from level 59 to 60, and the experience requirement will rise from there. The time to reach the upper Paragon levels approximates the long-term time investment required to get a level 99 character in Diablo II.
Additionally, more changes to the auction house have also been posted to the Diablo III forums that will be included with 1.0.4. A few of the changes you can expect to see include the option to cancel auctions at any time providing they have no bids, an increased size of gold stacks per listing, improved search functionality, UI Improvements and a number of bug fixes.