Officially: No
Hacked officially: Yes, by running this in the URL address:
javascript:window.document.getElementById('footer_utilities').setAttribute('class', 'clearfix clear rounded')
In the botttom-left corner a drop down menu will appear and you can change to a few themes (all are botched in one way or another besides "Zenimax", though)
Completely unofficially: Yes, through http://www.gamesas.com/index.php?/topic/1082909-forum-style-alterations
Still using a user style sheet myself, as the default skin is just fugly and faaaaar too dark for my liking.