Correct, the 4 pin connector is part of the new Intel psu specs. It supplies 12 volts (plus grounds) closer to the location that needs it.
The six pin connector is for the same purpose, but intended for server boards, as the ATX form factor is becoming more popular in rackmount applications. It's basically doing what Hoot's 5 volt mod is, only this time they integrated it into the motherboard. The pins it plugs into are usually right next to the power mosfets.