Intel has released Iris and HD graphics drivers for Windows 7 and Windows 8

This software driver package will install the Intel Iris and HD graphics driver for:

Intel Pentium Processor 2000/G2000/G2100 Series
Intel Celeron Processor 900/1000/G1000 Series

3rd Generation Intel Core Processors with:
Intel HD Graphics 4000/2500

4th Generation Intel Core Processors with:
Intel HD Graphics 4200/ 4400/4600/5000
Intel IrisTM Graphics 5100
Intel IrisTM Pro graphics 5200

These drivers will not function with any other product. View the README file for installation information and the RELEASE NOTES for driver version details. This driver package contains version 15.31.9.3165 (9.17.10.3165) for Windows 7* and Windows 8*.

Which file to choose:

Win32_15319.exe - This driver is in self installing format intended for end users.
Win32_15319.zip - This driver is in zip format intended for developers and IT professionals.

Usage:
These software drivers are generic versions and can be used for general purposes. However, computer original equipment manufacturers (OEMs) may have altered the features, incorporated customizations, or made other changes to the software or software packaging they provide. To avoid any potential installation incompatibilities on your OEM system, Intel recommends that you check with your OEM and use the software provided by your system manufacturer. Intel and the computer original equipment manufacturer (OEM) may not provide technical support for some or all issues that could arise from the usage of this generic version of software drivers.

Download for 32-bit
Download for 64-bit