I didn't jailbreak the phone to get this app specifically, but after i jailbroke the phone i found it there app store (free)... not sure if apple app store has anything like this.
Yes! jailbreaking the phone does void the warranty.. you have to weigh your personal felling about that. i personally am glad i did mine... But keep in mind im a bit more nerdy than most.
I downloaded one app that lets me record videos on the g2... even tho it doesn't have a video camera on it. Thats kind of neat.
I am able to download and change text/mail tones.
I downloaded a volume booster
I plan to explore it allot more over the weekend, but it has more than 7000 third party apps that apple doesn't want you to have.
How to Jailbreak Your iPhone Using BlackRain:
Step 1: Update iTunes to the latest version available and reboot your computer.
Step 2: Download BlackRa1n
blackweather and install it, then reboot your PC (note that rebooting is not necessary but I always do this as a precaution).
Step 3: Plug your iPhone to your computer and launch BlackRa1n. Click on “make it ra1n”.