Hi! Now is very popular wide screen monitors. It's more useful for using vertical oriented windows or bars like Google or Vista desktop sidebar (http://desktop.google.com/en/GB/?ignua=1). It was using in Yep (Mac OS biblio program similar zotero http://www.yepthat.com/view.html).
That сould be grate if one can switched between horizontal and vertical (right-hand side for example) orientation zotero tabs in browser window :)

Thanks!