StatusNet uses the GNU Affero General Public License. It is a flavor of the GNU General Public License dedicated to web services. The major difference to the GPL is the clause "if you make modifications to the StatusNet source code on your server, you *MUST MAKE AVAILABLE* the modified version of the source code to your users under the same license".
If you changed the source code of your StatusNet installation, you have to share the source with your users. You could upload your code on a source code hosting service. Note that Google Code does not accept the GNU Affero General Public License! A simple way to share your source code is to just create an archive (zip, tar) and link to it on your service.
Even the slightest source code change like adding Metatags enforces you to publish your source code.