As per the rumor mills, Apple is planning for a Fall media event on September 7, 2011 where it will launch (most likely) iOS 5 and iPhone 5 and as per the source which came from a Japanese Apple blogger Mitsunobu Tanaka, a.k.a. Kodawarisan Apple will start shipping iPhone 5 from this October.
Every Fall Apple holds a media event to announce about their new products which are due for release and this is no exception even this year. The actual date is yet be announced by Apple.
iPhone 5 was actually supposed to be released in June (as per the last three iPhone launches).