Sure, one high-end GTX 480 from NVIDIA crammed in your gaming rig is nice, but three of them is even better. The gang at Hardware.info have tested 3-way SLI with NVIDIA GTX 480 video cards.
In the end the publication found that three of the cards in one machine makes for the fastest gaming platform around today. The downside is that the cards need nearly 1000W of power, so you had better have a really big PSU.
The rig scored 22487 3Dmarks in the test system, which was a bit slower than HD 5970 CrossFireX in that benchmark. However, the NVIDIA rig made up that ground in gaming tests it seems.