Installing applications to an Android phone is simple, either use the Market application to find and install, put the apk file for the program on to your phone/SD card and install using Astro or finally you can use the adb push command to push the files to the phone. These are all fine methods of installing single programs to the phone but when you want to install a few programs/libraries/configs all at once you may be better using an Update.zip file with everything packaged up. The case for such a file is obvious when you want to add all of the Google applications to the AOSP builds of Android which would take a while rather than installing one update.