Here's an example:

gem install --format-executable rake
==> Installs executable "rake18".

ln -s rake18 rake
==> This step is performed by most Linux distros.

gem uninstall rake
==> Asks whether to uninstall "rake", but not "rake18".

Date: 2010-11-12 22:46
Sender: Ryan Davis

This ticket has been deemed stale and we're closing it in order
to catch up
with our ticket list. If you think it is still valid, please
reopen.

Date: 2010-10-25 17:05
Sender: Matthew Kent

We are migrating from ruby 1.8 and I'd love to see this as a
config option so gem removal works as expected.

Date: 2010-07-19 13:32
Sender: James Tucker

Indeed, this should not be used on a per command basis at all.

I'm thinking about removing it to avoid these problems,
and maintaining support purely by config file.

Date: 2010-01-14 18:51
Sender: Sven Schwyn

In fact, just add --format-executable to the uninstall command
and the case is closed as those using this option most likely
won't use it on a "per command" basis.