How to use Rake::PackageTask to create a zip file

I found out that the easiest way to build a WordPress plugin is using a rake task. In fact, you can use Rake::PackageTask to create a zip file. However, there is very little documentation about how to do it in practice. Here is my solution.

1. (destroy and) create a folder to hold just the needed files
2. copy the (possibly transformed) needed files to that folder
3. compress the folder

Here is my Rakefile:

Here are the tasks it creates:

Here is how you can use it:

Here is what you get: