Check out an in process App for Win 8 that makes use of TFS OData for planning poker

http://www.teamplanningpoker.com/HowTo/Win8/CreateYourFirstPlanningPokerSession

About:

Team Planning Poker was created by Mike Douglas and Deliveron Consulting Services to help distributed and co-located teams effeciently point your projects' backlogs that are using Team Foundation Server or Team Foundation Service.

Deliveron is a technology consulting company focused on delivering end-to-end solutions for clients. We have expertise in custom application development, system integration using BizTalk Server, enterprise portals and workflow with SharePoint, and data management and business intelligence using SQL Server.

Team Foundation Server and Team Foundation Service are part of Visual Studio ALM tools that help improve the effeciency and quality of development. Features includ Project Management, Requirements Management, Development, Test Case Management, Build Automation. There are several ways to start using TFS with little or no additional cost. Sign up with Team Foundation Service to get started.