MDX Studio is tool which helps users of Microsoft Analysis Services to analyze complex MDX expressions, monitor performance characteristics of MDX queries and get insight into how MDX interacts with other UDM features such as attribute relationships.
MDX Studio provides unique visualization representation of MDX expression and allows the user to interact with different stages of MDX execution. MDX Studio is aimed to be compatible with all the versions of Microsoft OLAP servers – OLAP Services 7.0, Analysis Services 2000, SQL Server Analysis Services 2005 and SQL Server Analysis Services 2008.
There is a forum dedicated to the tool on SSAS Info website.
The SkyDrive directory where you can find CTP releases is this: http://cid-74f04d1ea28ece4e.skydrive.live.com/browse.aspx/MDXStudio
It’s not a beta, it’s an alpha and there is space for a lot of improvements.