I'm using version .9.9.2.8 which appears to work fine on Firefox but there is a little glitch when you click on the Share/Save button in IE8. The menu does appear, but you get an "Error on page" message at the bottom of the original page.
Opening up this error reveals this:
Webpage error details
User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; GTB6; .NET CLR 1.0.3705; Media Center PC 3.1; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729)
Timestamp: Mon, 1 Jun 2009 00:37:47 UTC
Message: 'stories.0' is null or not an object
Line: 1
Char: 16402
Code: 0
URI: http://static.addtoany.com/menu/page.js