DDR3 is very late and very expensive, but it will come in two flavours. The memory manufactures will launch DDR3 in 1066 and 1333 MHz flavours. The 1333 parts will be the overclockable ones. Remember that DDR3 only needs 1.5 V to work, so there is some serious headroom for overclocking.
Intel wont be introducing its P35 chipset officially until the 4th of July, even though you've seen our review here of the same baby.
We are still working hard to get DDR3 samples, but even the big guys such as Kingston don’t have samples yet, not to mention the smaller fishes. This is supposed to change by the end of the May.
We still don’t know the suggested retail prices for DDR3 1066 and 1333 but I can promise you that it is going to be ridiculously expensive compared to DDR2.