At the moment you cannot create a 'report' from a work item query. We are looking into making this possible, though I can't give you a definite time frame as to when it would be available. However, there is support for creating a 'chart' in the dashboards using a work item query. If you take a look at this link:

https://jazz.net/jazz/web/projects/Rational%20Team%20Concert#action=com.ibm.team.dashboard.viewDashboard&id=_Glm7MKHQEdyhY-JOPv4EUw

You can see the 'Open assigned to me' viewlet; it is configured to create a chart based on the work item query of the same name.

To create a viewlet chart that operates on a work item query click the 'add viewlet' then under the Work Items drop down, select 'Work Item Statistics' - should be straightforward from there.