There are some posts claiming to know how to "hide" the My Site link:
One method is to simply remove permissions for all authenticated users to use social features via Central Administration. I don't like this big bang approach.
The other method (which I prefer) is removing the following from the masterpage:
<SharePoint:DelegateControl ControlId="GlobalSiteLink1" Scope="Farm" runat="server"/>
However I cannot find it in any master page!
In my case I actually have the "My Site" link hidden on a page and I am trying to recover it (i.e. activate the link again):
To get the link back I would have to know how to remove it in the first place (or find out how the developer did it) and I don't know how to do that as I tried on a fresh site to remove the link to no avail.