IAccessible2 is in the process of adoption as a an ISO Standard.  It will be late 2011 before the process is complete.

There are several parts to the standard, and they each follow a separate adoption procedure.  The documents are part of ISO/IEC JTC 1 / SC 35.

1. 13066-1 “Information Technology — User Interfaces — Interoperability with assistive technology – Part 1 Requirements and recommendations for interoperability”   This document is the actual standard, which explains the basic requirements of an accessibility API, then introduces and distinguishes the APIs on modern platforms, UI Automation, IAccessible2, Linux ATK, Apple Macintosh OS accessibility API, Java Accessiblity API (JAAPI), and WAI-ARIA (Accessible Rich Intenet Application) accessiblity API.  Each of the platform APIs are detailed in separate subparts of the stardard called Technical Reports.
2. 13066-2 “Part 2: Windows Automation Framework accessibility API“  This technical report provides detail on MSAA and UIAutomation.
3. 13066-3 ” Part 3: IAccessible2 accessibility API”
4. 13066-4 “ Part 4: Linux / UNIX graphical environments accessibility API”
5. 13066-5 “ Part 5: Apple Macintosh OS accessibility API”
6. 13066-6  “Part 6: JAVA accessibility API”
7. 13066-7 “ Part7: WAI-ARIA (Accessible Rich Intenet Application) accessiblity API”

As of August 2010, the base standard (Part 1) along with the technical reports on Microsoft UIAutomation (Part 2) and IAccessible2 (Part 3) have passed subcommittee review and are now out for ISO review.  Comments will be gathered and addressed. They should be voted on and approved in February 2011.

The parts on Linux/Unix ATK (Part 4) and the Java Accessibility API (Part 6) are being written and will go out for a committee review in December 2010.

The parts on Apple OS API (Part 5) and WAI-ARIA API (Part 7) do not have editors and are not actively being written.