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