Enesys RS Data Extension 3.6.26 fixes a small bug that was introduced in version 3.6.23. This bug forces you to edit a query in XML mode when IsNull or IsNotNull conditions are being used with Lookup and DateTime columns. Note that this bug does not affect the proper execution of the query.

Enesys RS Data Extension 3.6.26 also adds support for XML namespaces to the XmlQuery statement. It is therefore possible to specify a namespace when filtering XML through the ElementPath property (ie: //my:item).
Even though this may not seem like a major feature, support for namespace has some interesting use with InfoPath forms by letting you include in your reports fields that are not published as SharePoint columns. A knowledge base that explains how to do this is in preparations.