The new REST Data Services node in the browser in 4.2 ea2 is very nice for quick development of REST modules.
What is missing is a simple way to create scripts to generate the developed modules (and roles and privileges) in another database (e.g. for promotion to test/prod). Now I copy the statements from the statements log directly after creation or modification, and paste them into a script, but that is just a workaround.
If the modules and templates (with handlers and parameter definitions) could each be saved in a separate script (or optionally evevrything of a module in 1 script) then it would be easy to do versioning by checking in in git or svn.