The recent Mac OS X 10.5.8 update did not affect flashed PC version of Radeon HD 4870 installed in Mac Pro, however, it disabled the 3D acceleration for the Radeon HD 4890. To fix this problem Netkas just released a modified instruction set in order to bring back compatibility with the last version of Leopard. You can download it from: http://rapidshare.de/files/48062862/QE_CI_Exotic_cards_10_5_8.pkg.html
His work really unchained Mac Pro users from using only Mac Edition version of graphic cards, and finally get access with a rather simple procedure to the best PC models on the market.