From what I've seen, people have shown that when you have an SLI or Crossfire setup, CPUs can at times hold them back. That's why Intel Sandy Bridge has been so good, too. However, I look at my system, I see the constant 99-100% GPU usage on my single graphics card and could not justify a bottleneck...
Since I see SLI and Crossfire simply to increase NVIDIA's/AMD's annual revenue (not really for NEED, especially with today's games), I see no point in having more than one graphics card and thus see no point in speaking of bottlenecking. Not in my case, anyway, from what I experience with my particular system.
Having said that, if AMD Bulldozer pulls through as being better than Intel Sandy Bridge in performance and is similar for overclockability AND on top of that I can get an eight-core one with my current motherboard (according to Asus, I will be able to), then I'll happily get and AMD Bulldozer CPU. If it doesn't live up to the hype, I will wait until Intel Ivy Bridge is out, or whatever they release after. As for graphics card, this overclocked Radeon 5870 eats EVERYTHING with no visible lagging. Once it lags, on eBay it goes and in comes perhaps a Radeon 7000 series or GeForce 600 series card (just one, because more than one is silly!