This is topic which we already discuss with my colleagues several times and for now we don't have plans for it.
In most cases it's better to generate XML/YML/PHP schema and let ORM framework generate SQL query. Each ORM uses own way how to convert model to SQL (how to represent many-to-many, inheritance etc.)
In the future we want to focus on another ORMs (like Java Hibernate or JPA you mentioned), support migrations and another ORM-like features instead of SQL like-features.
On the other side it wouldn't be hard to create XSLT template which converts XML model to SQL queries, maybe maintained on the community base. In this case we will be happy to help with initial steps.