How do I release my application as a tarball?

You need to have the kdesdk module on your machine. In this module, kdesdk/scripts/cvs2dist is a script to extract an application from the kde source tree and package it as a standalone application.

From the command cvs2dist --help, you get:

Usage: cvs2dist module directory [options] [addfile1] [addfile2] ...

Provided that your application is in the kdenonbeta module, that your application name is KMyApp, the command you will issue is:

$ cvs2dist /path/to/your/cvs/source/kdenonbeta/ kmyapp -n kmyapp -v 0.1

where you replace kmyapp by your program name and 0.1 by your program current version.

This will create two packages kmyapp-0.1.tar.gz and kmyapp-0.1.tar.bz2, in the directory where you issued your command.