UPDATE: Here is a different set of instructions that is specifically for beginners, including an app that does most of the work for you: http://androidandme.com/2009/08/news/how-to-root-a-t-mobile-g1-and-mytouch-3g-android-phone/
Please note: I have recently switched from JF 1.5.1 to the latest Cyanogen ROM (v.4.0.2). More details are available here: http://forum.xda-developers.com/showthread.php?t=537204
With the G2 out and a total of 18 Android phones expected by year’s end, I am happier than ever with my G1. Why? Because I have root access and a second battery There are lots of forums and blogs that describe how to root a G1 Android phone, but first I want to focus on why you might want actually want to do it.
Others have compiled lists of pros and cons for rooting the G1 phone, but I want to focus more on the specific apps that make rooting the G1 totally worth it to me. Normally, Android only lets you copy/paste links, but the rooted G1 (running JF 1.5.1) has a nifty feature that let’s me copy text from anywhere. (I do this a lot, so this is one less reason to bring the laptop.) With a rooted G1 you can hold Shift, scroll anywhere on the screen, click the scroll ball once to start selecting, and click it again to stop the selection — it automatically copies your selection to the clipboard. It also has a the iPhone’s multi-touch feature for the browser, if you care about that kind of stuff.
- Wifi tether (free here) — This is the single coolest reason to root your G1 phone. It allows your to use your G1′s data connection as a wifi access point. This is great alternative when staying in a hotel that charges for wifi. For those on a 3G network, this is actually pretty fast (a little less than DSL speeds). The G1 will prompt you when someone is trying to connect, so you can control who uses it. (It also works via Bluetooth, if you prefer that.) I’ve used wifi tether to create a mobile access point in the car. My wife used it to surf around on her iPod Touch on a recent road trip. Very cool.
- Backup for Root Users (free on Android market) — Backs/restores all your apps and settings to your micro SD card. Even compatible with App2SD.
- SetCPU (costs $0.99) — This app overclocks the G1 up to 528 MHz (384 is normal) when you are using it or when it’s plugged in, and can also “underclock” the processor down to 128 MHz when in sleep mode to save battery life. No reported problems with this level of overclocking. Very cool!