Update 2013-10-19: Check out https://github.com/pymander/evernote-mode for a possibly better way to do things. =)

This is totally raw and needs a lot of hacking, but look, I can dump subtrees from my Org notes into Evernote using Emacs Evernote Mode. The desktop app handles these perfectly, although the Android app does funny things to the whitespace if you edit the note. Still, great as a reference!

Mwahahahaha!

(defun sacha/org-get-subtree-region ()
  "Return the start and end of the current subtree."
  (save-excursion
    (let (beg end folded (beg0 (point)))
      (if (org-called-interactively-p 'any)
          (org-back-to-heading nil) ; take what looks like a subtree
        (org-back-to-heading t)) ; take what is really there
      (org-back-over-empty-lines)
      (setq beg (point))
      (skip-chars-forward " \t\r\n")
      (save-match-data
        (save-excursion (outline-end-of-heading)
                        (setq folded (outline-invisible-p)))
        (condition-case nil
            (org-forward-same-level (1- n) t)
          (error nil))
        (org-end-of-subtree t t))
      (org-back-over-empty-lines)
      (setq end (point))
      (list beg end))))

(defun sacha/org-post-subtree-to-evernote (&optional notebook)
  "Post the current subtree to Evernote."
  (interactive)
  (let ((title (nth 4 (org-heading-components)))
        (body (apply 'buffer-substring-no-properties (sacha/org-get-subtree-region))))
    (with-temp-buffer
      (insert body)
      (enh-command-with-auth
       (let (note-attr)
         (setq note-attr
               (enh-command-create-note (current-buffer)
                                        title
                                        notebook
                                        nil "TEXT"))
         (enh-update-note-and-new-tag-attrs note-attr))))))       

In other news, I now have book notes from 156 books in my Evernote notebook. Mwahahaha! Time to add more.