Ask HN: building a database middle layer to work of ODBC?

Ok, so here is the basic problem a friend and I are trying to tackle. We want to build a service that will appear to our customers as a MySQL or PostgreSQL but would in fact be an application layer. The application (perhaps coded in Python or Ruby) would take requests over ODBC such as inserts and select statements and give expect ODBC responses. Before we try and reinvent the wheel, are there any projects out there doing something like this currently? How would you go about it?