There's now an instant method to get third party apps on your iPhone (firmware 1.1.1 only). The same methond works on iPod Touch. I have to say, this is by far the easiest method of hacking the iPhone that I've ever seen. This method, which relies on the iPhone TIFF vulnerability, is also incredibly simple to use; much more so than the previous AppTapp installer method for iPhone 1.0. Since it relies on a buffer overflow, I expect this method to stop working as soon as Firmware 1.1.2 is released, which could be any day now.
All you have to do is point your iPhone browser at jailbreakme.com, confirm the wish to jailbreak, read some stuff, scroll down, select 'Install AppSnapp', wait for Safari to quit, and wait. Your iPhone or iPod Touch should restart automatically, and when it's all done, you'll have Installer.app ready and willing for you to install 3rd party apps!
This method of installing 3rd party apps doesn't require any computer software, you just have to go to the website on your iPhone browser and follow the instructions. Again, the site makes efficacious use of the TIFF exploit that's been talked about before, so if using a security vulnerability to install software freaks you out, don't go to the site I've posted after the cut.
Conversely, f you think that using a buffer overflow to install software is awesome, 31337, or k-rad, there's a link for you and your iPhone after the break.