As previously mentioned, installing the iPhone software/firmware update 1.0.2 will erase any previously established hack and eliminate any third-party binary applications. If you want to re-hack your iPhone after the 1.0.2 software update, there are two options:
Option #1: Use Installer.app single-command choose firmware 1.0.1
Use this previously mentioned method, which utilizes the Installer.app single-command, on an iPhone updated software/firmware version 1.0.2. When you are prompted to select a firmware version, just pick 1.0.1 (even though your iPhone is actually running version 1.0.2). The process should complete smoothly (it did in-house), and your iPhone will still have firmware version 1.0.2 installed -- you can check this by going to tapping Settings, then General, then About and looking next to Version. 1.0.2 (1C28) should be displayed.
This method has the distinct advantage of automatically placing Installer.app on your iPhone, making it much easier to re-install third-party applications, especially over a Wi-Fi connection. However, we're not sure if any stability problems will ensue from using the 1.0.1 firmware to hack a 1.0.2 firmware phone.
Option #2 Use the 5-step process with the new firmware
We've updated our 5-step process for putting third-party applications on the iPhone to include a link for the new iPhone 1.0.2 firmware file, which can be used in conjunction with your other tools to hack the device. Again, we're not sure if there is any benefit to matching the firmware files -- but there may be.
Once you've performed this process, you can add Installer.app via the scp command as mentioned here.