yes if you upload a map to your file share people can download it (inculding bungie) I have a thread where you can share maps or game types here.
Heres how to do it.
press start go to file share select an empty slot and upload a movie,map,gametype or screenshot. Then if some one looks at your service record they can download it and play it.
Diamond- Name- XEIN FC- 3823 5547 8764
Battle Revolutiom- name XEIN code 1031 8278 1971