How many people here have experimented with multi clocking with SLI? Just a flexibility feature that sometimes can be useful. Since you can mix and match different vendors nowadays and different clocked boards. You can run a handful of SLI clocks nowadays. Useful if one card will overclock higher than the other. There are slight benefitsto doing this performance wise. Much like SLIng a 9800GTX with a 9800GTX +.
But my GTX 260-216 running with 2 260- 192's running different shader clocks is just an example. Lots of flexibility here.