Actually getting some conflicting info on the release date. Looking like first half of 2013 around the same time that IB was released, which i thought was much more likely. Waiting til the end of 2013 or Q1 2014 would violate Moore's law i would think Plus since they already have some in testing, though they're the Xeons, doesn't make sense that it would take that much longer. So i figure June next year at the latest.
You will need a new mobo for Haswell/Broadwell. It'll use socket 1150.
Also as i mentioned it'll use DDR4 which will be available later this year, though probably not for sale since nothing will exist right away that it can be used for.
For saving power, DDR4 uses lower voltage than DDR3: 1.2V or less, compared to ~1.5V. Also, DDR4 data transfer rates will range from 2133 to 4266 MT/s according to JEDEC specs. DDR3 only achieves 800 to 2133 MT/s. RAM per stick should easily reach 32GB in 2013.