Yes, this is possible through record types and page layouts.

To make this work, you will need at least two Opportunity record types, including one record type for closed/Won opportunities.

Create a workflow rule and field update to update the record type based on when the opportunity changes to closed/Won.

Then, create page layouts and use page layout assignments to dictate when the button appears.

Mike Gerhold, aka button click admin, has written a blog post on extending this functionality throughout the sales process here: http://buttonclickadmin.com/monday-am-admin-the-goose-and-the-gander/

Yes, this is possible through record types and page layouts.

To make this work, you will need at least two Opportunity record types, including one record type for closed/Won opportunities.

Create a workflow rule and field update to update the record type based on when the opportunity changes to closed/won.

Next, create page layouts and use page layout assignments by record type to dictate when the button appears.

Mike Gerholdt, aka button click admin extraordinaire, has written a blog post on extending this functionality throughout the sales process here: http://buttonclickadmin.com/monday-am-admin-the-goose-and-the-gander/