Added the link icons plugin from blueprint 0.8. To install this plugin:

compass -f blueprint -p link_icons

frameworks/blueprint/stylesheets/blueprint/modules/_link_icons.sass

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+=no-link-icon
+  :background transparent none !important
+  :padding 0 !important
+  :margin 0 !important
+
+=link-icon-base
+  :padding 2px 22px 2px 0
+  :margin -2px 0
+  :background-repeat no-repeat
+  :background-position right center
+
+=link-icon(!name, !include_base = true)
+  @if !include_base
+    +link-icon-base
+  :background-image= image_url("link_icons/#{!name}")
+
+=link-icons
+  a[href^="http:"],
+  a[href^="mailto:"],
+  a[href^="http:"]:visited,
+  a[href$=".pdf"],
+  a[href$=".doc"],
+  a[href$=".xls"],
+  a[href$=".rss"], 
+  a[href$=".rdf"],
+  a[href^="aim:"]
+    +link-icon-base
+  a[href^="http:"]
+    +link-icon("external.png", false)
+  a[href^="mailto:"]
+    +link-icon("email.png", false)
+  a[href^="http:"]:visited
+    +link-icon("visited.png", false)
+  a[href$=".pdf"]
+    +link-icon("pdf.png", false)
+  a[href$=".doc"]
+    +link-icon("doc.png", false)
+  a[href$=".xls"]
+    +link-icon("xls.png", false)
+  a[href$=".rss"],
+  a[href$=".rdf"]
+    +link-icon("feed.png", false)
+  a[href^="aim:"]
+    +link-icon("im.png", false)

frameworks/blueprint/templates/link_icons/link_icons.sass

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+@import blueprint/modules/link_icons.sass
+
+// This turns link icons on for all links. You can change the scoping selector from
+// body to something more specific if you prefer.
+body
+  +link-icons
+  // Use this class if a link gets an icon when it shouldn't.
+  a.noicon
+    +no-link-icon
+  // Not all links have a url structure that can be detected,
+  // So you can set them explicitly yourself like so:
+  a#this-is-a-pdf-link
+    +link-icon("pdf.png")

frameworks/blueprint/templates/link_icons/manifest.rb

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+stylesheet "link_icons.sass", :media => 'screen, projection'
+
+image 'link_icons/doc.png'
+image 'link_icons/email.png'
+image 'link_icons/external.png'
+image 'link_icons/feed.png'
+image 'link_icons/im.png'
+image 'link_icons/pdf.png'
+image 'link_icons/visited.png'
+image 'link_icons/xls.png'