As a PC gamer, I can tell you one powerful video card like the GTX 480 is great. A pair of the beasts in SLI is even better, assuming you have the PSU for it.
If two of the powerful cards is a good thing, then four would be enough gaming nirvana to send many geeks over the edge. According to TechReport, EVGA has confirmed that the GTX 480 will support 4-way SLI.
The board used in the test was the EVGA X58 Classified with 4-way SLI support. However, it's not the only board that supports 4-way. I can't imagine how big a PSU you would need to support four of those cards along with a high-end CPU.