The workflow comes with two distinct feature groups:
Speak the active application's text with a specific voice; useful for multilingual setups where you want to have text spoken in one of several languages on demand. For instance, you could have one global keyboard shortcut for speaking text in English, and another one for Spanish.
Speak specified text with one or more voices, selectable by name(s) or language(s); useful for interactive experimentation with multiple voices, such as to contrast regional accents.
For details, see the repo.
Here's the direct download link to the most recent stable version (this link will remain current).
However, I suggest installing via the npm registry, if you have Node.js installed - if not, consider installing it just to benefit from its great package manager, npm; try curl -L http://git.io/n-install | bash ):
[sudo] npm install -g speak.awf
The advantage of this installation method is twofold:
Remembering only the package name is sufficient to install the workflow (again).
More importantly: It's easy to update the workflow to its latest version:
[sudo] npm update -g speak.awf
If the latest version is already installed, no action is performed.