Sharing to social pages with django
If you want only specific 'share buttons' or with default style justy type " social_name 'share button' " and you will get the js to include on your site (here are the 3 you mentioned in post):
http://www.facebook.com/share/
http://twitter.com/goodies/tweetbutton
http://www.google.com/buzz/api/admin/configPostWidget
If you already have the app written to behave like mashable, one approach is to put the login dialog (if it's needed) in a jQuery dialog. http://jqueryui.com/demos/dialog/