A share button in the browser is my favorite solution. Twitter and Facebook aren't tracking you, there aren't embeds to slow down sites, and the user knows where the button is every time.
I think IE, of all things, had a feature a few releases back for exactly this scenario: a page could define some markup around the content that was shareable, and users could add browser plugins that picked them up and published them wherever they wanted. Does anyone remember what it was called?
Not sure why it's a surprise that IE would add features that require proprietary markup.
Accelerators? http://ie.microsoft.com/activities/en-en/Default.aspx