Sounds like EsperJDBC and Aleri JDBC/ODBC capabilities have found some echo. Coral8 just announced interoperability with ODBC with its 5.6 minor release - 3 months after EsperJDBC introduction.
The Coral8 documentation states that Coral8 now can expose public windows (equivalent of Esper named windows) over ODBC and not just only with a proprietary SDK.
If you want to explore this concept with Esper - this slide deck is a must read:
A demo also demonstrates how you can perform ad-hoc queries on your CEP real-time data and computations using any JDBC compliant tool - namely Actuate / Eclipse BIRT and create dashboards in minutes.
(Note: EsperJDBC is not open source and only available in EsperTech' commercial offering although you can access free trials)
(Note: Post updated as per Jeff comment on Aleri)