I've tried deploying a simple grails war with no luck. The spring framework appears to load fine. Giving that spring and grails are essentially servlets and pojos it should in theory be straightforward. I think this would be the killer feature for winstone to support. The aspriation of both technologies is similar: grails wishes to make web development quick, simple and painless - winstone wishes to do the same for web deployment. This could be a unique selling point the really raises the profile of winstone. I've attached a simple 'hello world' war as an example.