According to Xbit labs Haswell will not only improve performance and feature some tricks to lower power consumption, but will use a VRM as a secret weapon. This will improve the granularity of power supply to central processing units and thus further cut power consumption without compromising performance.
VRMs usually sit on the mainboards, but recently, multi-phase CPU power supply circuitries were bought in. While these are not bad they cost a bit and take up too much space on mainboards. They also do not improve granularity and performance as well as Intel needs.
Xbit has found evidence that Intel has developed a special programmable chip with 20 power cells. Each power cells is a mini VR with analogue circuits rated for up to 25A electric current and supporting up to 16 phases. Potentially, one 20-cell chip enables 320 power phases per CPU, which allows extreme granularity of power supply. Apparenly Intel will install the integrated voltage regulator (IVR) chip, which will be made using 22nm process technology onto the same substrate with Haswell microprocessors.
Ultimately Chipzilla will build an IVR into microprocessor to further improve granularity of power supply. This will probably appear in Broadwell chips for notebooks, but also for various system-on-chip solutions for smartphones and tablets.