I started giving some visibility to this story on several websites. Hope we reach the owner.
http://www.reddit.com/r/reddit.com/comments/9di8t/please_reddit_help_me_find_owner_of_iphone_lost/
http://digg.com/travel_places/Found_iPhone_in_Venice
http://venice.en.craigslist.it/laf/1339189073.html
http://forum.virtualtourist.com/discussion-486227-1-1-Travel-0-0-Venice-discussion.html
http://www.boston.com/community/forums.html?plckForumPage=ForumDiscussion&plckDiscussionId=Cat%3aTravelForum%3a10635Discussion%3a7998dbaf-9a05-477a-986f-91206641dfe3
http://forums.pressdemocrat.com/eve/forums?a=tpc&s=2151084365&f=7111054036&m=8921060119&r=8921060119#8921060119 (thanks Greg)
http://sfgate.kaango.com/feViewAd/15183657