The easiest way to add this line when creating new buttons.
$(this).button();
eg
(jQuery to create button) function(){
$(this).button();
}
I think you could just just call it again, but it could be slower.
$('input:submit').button();
EDIT: after looking at what jQuery.tmpl you could do something like
$("#sometmpl")
.render( arrayOfDataObjects )
.appendTo("ul" function(){
$("#sometmpl input:submit").button();
)};
but do not keep me in this.
OR take a look at jquery ui css and just add the classes needed for submit buttons. Guidance may not work though
class="ui-button ui-widget ui-state-default ui-corner-all ui-button-icon-only"