Quoth the Maven

1) BACK UP YOUR PHONE in iTunes, sync it, take a deep breath.

2) To upgrade your phone to iPhone OS 3.0, follow this guide to the letter; pick your platform (Mac / Windows / Linux). Links on these pages will allow you to download the four files you’ll need: redsn0w, the IPSW, and the two bootloaders if you need to unlock. Note: DO NOT INSTALL ICY at this time. Also, be sure you download the most current version of redsn0w (0.8 at the time of writing).

2a) If you get a curious delay/hang/pause longer than a few seconds at step 11 of the iClarified guide, simply unplug and replug the iPhone USB cable quickly. This will kick it’s butt into the required reboot, and allow the process to finish.

3) Your now activated (hacktivated, really), unlocked and jailbroken iPhone is ready for it’s makeover. Plug it into your computer, introduce it to iTunes, and do a “restore from backup” to port all your old files and settings over to the upgraded device.

4) But wait! YouTube, Notifications, and MMS are all not enabled :( No worries. First, open up any application that has push notifications (AIM, IM+, Beejive, etc), dismiss the notification pop up, and close the app. Now go to the iPhone settings and DISABLE notifications for now.

5) Back to iClarified: follow this guide, but MAKE SURE you’ve completed step 4 first, otherwise it won’t work. Once YouTube is working, you’re home free (notifications will work also, but…)

5a) (…beware the effect the notifications, as they seem to mercilessly slaughter battery life. You might want to keep them off for now, but do the patch to regain YouTube function.

6) To get MMS working, start with this guide, and then go get these T-Mobile carrier bundles. NOTE: pick the one that’s right for your phone/data plan. Look at your wireless APN to match it up - you’ll usually be Postpaid/Flexpaid regular or Legacy. Be sure to reboot your phone at the end.

That’s about it - the guides are really comprehensive, but there are some tiny little bits (like the USB unplug trick) and certain key order-of-operations actions that go unmentioned in some of the guides.