Yes. See {{DISPLAYTITLE: }} and $wgAllowDisplayTitle http://www.mediawiki.org/wiki/Manual:$wgAllowDisplayTitle
There're also several javascript hacks to do the same.
Doesn't DISPLAYTITLE only allow titles that reduce to the same canonical form? (eg. "Wikipedia" could be called "wikipedia", but that's about it)
Since 1.14 you can set $wgRestrictDisplayTitle = false to disable that restriction. However, that would still not allow links or formatting in the title.
-- daniel