The official release is planned for Q1 2013. We'll also have a BETA release in Q3 this year (most probably in the middle of October). We'll do our best to include this functionality for the BETA release, but we have a lot of work with other RadPivotGrid features which have higher priority. Of course as I already said this will be part of our official release.
Don't hesitate to contact us if you have any other questions regarding telerik products.
the Telerik team