Alongside today's news that Apple has finally released the iPhone/iPod Touch OS 3.0 to the public (download it by opening iTunes, connecting your iPhone or iPod Touch and clicking the 'Check for Update' button), some websites are noting that it is easy to enable tethering on your iPhone, even if AT&T hasn't officially announced support for this feature.
Tethering is great for small Internet browsing sessions, or when your iPhone just isn't enough to do what you need to do (for instance, adding content to a website, or uploading a large file). But don't Tether too much: First, if a lot of people are tethering, it can slow down the network for everyone else, and second, your iPhone's battery takes a huge hit (even if charging) while you're using it's 3G signal for tethering.
[NOTE: Visual Voicemail may stop working after you follow the steps below. To get it back, simply go to the Settings app, tap on General, then Network, then Cellular Data Network; tap on the "Visual Voicemail" APN and change it from wap.cingular to acds.voicemail.]