Another update (09/03/09): public access to google invoice template has been removed, click here to read more.
Update: for some reason editing permission to the world doesn't work anymore. If you need to use this invoice template, please find a way to request access in the menu, and I shall grant you full access.
For some reason I started getting access requests for my free google invoice. I thought first that people were bored and just did it for fun of it, but turns out that no, indeed access has been blocked for other users. I logged in with my other gmail account to check. I don't know what happened, maybe google changed permission system. I don't recall how this looked one year ago when I did it.
I have thus re-enabled "Share with the world" option. Keep enjoying free google invoice template.