Here is what you need to do if you would like your library or tool to be added to the list of contributions on the Processing site.
Make sure your distribution package is Processing 2.0 ready. This simply means adding a library.properties or tool.properties file at the root of the project folder.
Send a message with the links to your library or tool to the Processing Librarian, which is currently myself. You can DM me here or e-mail me at prisonerjohn+p5@gmail.com.
The Eclipse templates have also been updated to generate these .properties file, and this should make the process even easier. Here are instructions for a
library and for a
tool.