Apple on Friday released an update fixing an SMS security flaw with the iPhone. However, the update does not disable at least one of the hacks that enables tethering on AT&T’s network. One reader contacted me soon after installing iPhone OS 3.0.1 and confirmed that tethering using the “iPhone Help Center” was still working. This person has a stock iPhone 3GS that has not been jailbroken or hacked in any way.

Tethering has been a sore spot for many users since Apple announced that it was an option, but AT&T has not allowed it for iPhone users. There has been a lot of speculation on the reason AT&T won’t allow iPhone users to access the network, but the company hasn’t budged yet.

I weighed-in on the subject last month. I believe that AT&T is afraid of how much iPhone users will take advantage of the tethering and MMS and possibly crash the network.