Asus announces new ATI HD 4870 X2 based graphics cards with the ASUS EAH4870X2/HTDI/2G and the ASUS EAH4870X2 TOP.
The ASUS EAH4870X2 TOP/HTDI/2G and EAH4870X2/HTDI/2G are slated to be upgraded soon with a specially designed fansink for efficient heat dissipation.
These upgraded graphics cards will utilize a specially designed fansink to effectively dissipate heat away from both GPUs – enabling much more stable performances in comparison to reference designed single fansinks. In addition, they will also be equipped with an EMI shield, which reduces EMI Interference by 66% for more stable signals; and DIP Spring Chokes will lower temperatures by 5~10°C in comparison to traditional Toroidal Coil Chokes. Furthermore, the LF PAK MOS guarantees more efficient power and less heat production; and on top of all this, Japan-made polymer capacitors will lower power loss for more stable operations. In this way, users will be able to enjoy extreme performance and have peace of mind over product lifespans – only with the second version of the ASUS EAH4870X2 Series.

If I understand the Asus press-release correctly you should wait until the 2nd generation of the ASUS EAH4870X2 cards to benefit from the new heatsink design.
More details on the Asus site.