Into mobile reports that the iPhone firmware update 3.1 might go live on the 9th along with the music event. This update is expected to bring AR support officially with some Augmented Reality apps launching in the same week.
Apple would certainly like to use a big platform to announce this. Also interestingly iTunes 9 is expected to come out with some great social features. Probably iPhone OS 3.1 would bring some goodies specially for itunes 9 aswell.
What more adding to the rumors is the speculation that AT&T is ready to offer MMS for the iPhone and this might also go live with OS 3.1 and get official at the Spt 9th Rock n Roll event.