You can still test it out by using the viewer to open files on the web, without having to log in; this can be pretty useful in its own right. Here's a bookmarklet that opens the link you click immediately afterwards in Docs Viewer:

    javascript:var link,l=0;while(link=document.links[l++]){if(link.href.toLowerCase().indexOf('.pdf')!=-1||link.href.toLowerCase().indexOf('.ppt')!=-1||link.href.toLowerCase().indexOf('.tiff')!=-1||link.href.toLowerCase().indexOf('.tif')!=-1||link.href.toLowerCase().indexOf('.pptx')||link.href.toLowerCase().indexOf('.xls')||link.href.toLowerCase().indexOf('.xlsx')||link.href.toLowerCase().indexOf('.pages')||link.href.toLowerCase().indexOf('.ai')||link.href.toLowerCase().indexOf('.psd')||link.href.toLowerCase().indexOf('.dxf')||link.href.toLowerCase().indexOf('.svg')||link.href.toLowerCase().indexOf('.eps')||link.href.toLowerCase().indexOf('.ps')||link.href.toLowerCase().indexOf('.ttf')||link.href.toLowerCase().indexOf('.xps')&&link.href.indexOf('javascript')==-1&&link.href.indexOf('file:')==-1){var newString='http://docs.google.com/viewer?url='+link.href;link.href=newString;}};void(null);