Change the dev-root and stick this somewhere in .emacs.d/

gistfile1.el

(defvar dev-root "/Users/davidsnyder/Development")                                                                                              
                                                                                                                                                
(defun git-current-branch ()                                                                                                                    
  (substring (shell-command-to-string "git branch | grep '\*'") 2 -1))                                                                          
                                                                                                                                                
(defun ics-github-link ()                                                                                                                       
  (interactive)                                                                                                                                 
  (let ((path (split-string (file-relative-name (buffer-file-name) (dev-root)) "/")))                                                           
    (message (concat                                                                                                                            
              "https://github.com/infochimps/"                                                                                                  
              (car path)                                                                                                                        
              "/blob/" (git-current-branch) "/"                                                                                                 
              (mapconcat 'identity (cdr path) "/")                                                                                              
              (format "#L%d" (line-number-at-pos))                                                                                              
              ))))