As mentioned before we don't plan to have a Payroll Module as it would not belong in an HRM application.
However, we could consider having some payroll related functionality that make sense in an HRM application.
Our roadmap is more or less defined by users of the product. We have a place in our wiki where users could come in an define the features they want:
http://www.orangehrm.com/app/wiki/index ... nge_Future
Feel free to update this wiki page with details of the features you would like to see and based on responses from other users we can consider implementing this in near future.
Note the text in bold are features we're in the process of implementing now.