Backtick codeblocks now correctly replace & with & and Textile support for back tick code blocks has been removed. It never really worked. Textile makes me sad.

plugins/octopress_filters.rb

@@ -30,22 +30,17 @@ module OctopressFilters
     input = input.gsub /<p>`{3}\s*(\w+)?<\/p>\s*<pre><code>\s*(.+?)\s*<\/code><\/pre>\s*<p>`{3}<\/p>/m do
       lang = $1
       if lang != ''
-        str  = $2.gsub('&lt;','<').gsub('&gt;','>')
+        str  = $2.gsub('&lt;','<').gsub('&gt;','>').gsub('&amp;','&')
         highlight(str, lang)
       else
         "<pre><code>#{$2}</code></pre>"
       end
     end
 
-    # Textile support
+    # Textile warning
     input = input.gsub /<p>`{3}\s*(\w+)?<br\s*\/>\n(.+?)`{3}<\/p>/m do
       lang = $1
-      str  = $2.gsub('&lt;','<').gsub('&gt;','>').gsub(/^\s{4}/, '').gsub(/(<br\s\/>)?$/, '')
-      if lang != ''
-        highlight(str, lang)
-      else
-        "<pre><code>#{$2}</code></pre>"
-      end
+      "<pre><code>Back tick code blocks are not supported for Textile.\nTry HTML or Markdown instead or use the codeblock tag.\n\n{% codeblock #{lang} %}\nYour code snippet\n{% endcodeblock %}</code></pre>"
     end
 
     # Regular HTML support