The new release 1.0.0.M1 is out, here is the list of changes. Again there are incompatible changes to the API and that can happen until we release the stable version (1.0.0.RELEASE). Among the changes, you can find a new option (–addBlanks) for the merge command to add a blank page after each merged document if the number of pages is odd.
Andrea & Eduard
Is there a commandline interface for Mac, to merge pdfs, called programmatically? pdftk works ok for this on windows but not on mac
sejda-console is the command line interface written in Java and it runs on every platform where a Java Runtime Environment (version 5 or above) is available.