Since Nvidia released the 9800 GTX+, an overclocked GTX 9800, it is AMD's turn to counterattack now.
Will there be overclocked versions of the HD 4850 soon?
This won't be done by AMD themselves but by the card manufacturers: AMD eased the overclocking regulations for the HD 4850. Therefore it won't take long for some overclocked cards to emerge.
According to tgdaily.com, the clock speed of the chip will be set 50 MHz about the default value and the memory bandwidth is said to be increased by 5 to 6 GB/s, which might be achieved with a moderately increased memory clock speed.
Additionally the cooling is said to be adjusted for the overclocking - a dual slot solution seems appropriate to deal with the produced heat.