I have a script:
$(\'#hfont1\').hover( function() { $(this).css({\"color\":\"#efbe5c\",\"font-size\":\"52pt\"}); //mouseover }, function
The example from jQuery's website animates size AND font but you could easily modify it to fit your needs
$("#go").click(function(){ $("#block").animate({ width: "70%", opacity: 0.4, marginLeft: "0.6in", fontSize: "3em", borderWidth: "10px" }, 1500 );
http://api.jquery.com/animate/