This extension adds a toolbar to VS, that is similar to the Web Deployment toolbar. It allows you to set up a profile (you input your CodePlex username/password and a few other fields). Once that is set up, and your project is correctly set up for ClickOnce publishes, you can simply publish using the toolbar, instead of going to your project's web page, and creating a release there.
You also have the ability to replace an existing release: that is, if a release with the specified name already exists, the extension can simply edit its description, etc. and upload the new publish zipfile.
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