The UI of meego harmattan doesn't exactly look like maemo. They may share minor similarities but harmattan looks literally different to me. I'm talking in terms of judging by the videos that the lucky N950 devs posted. Also you said no to those three but it seems like you missed out, WP7, Blackberry, moblin and the codename maltemi. Oh there's S40 and I think QNX? maemo is dying and unfortunately meego for handhelds seems to be also dying. Meego as far as I can see requires a mobile phone manufacturer to produce the required device since nokia was the first to pull out of the joint venture with intel.