K10 motherboards will only use DDR2-1066 until they move to DDR3 (which will happen with AM3/45nm CPU's - which will also work in AM2+). And overclocking K10 is done a lot better with multiplier increasing rather than HTT bus increasing.
even then, with their IMC, DDR2-1066 should be more than enough to feed the cores, even past 3GHZ. And you can still get good latencies at DDR2-1066 depending on what modules you get.