My friend dropped her iPhone 3GS and the screen shattered. The touchscreen still worked so I decided it was worth fixing.
Great! The iFixit parts and tools were just what I needed. I finished in under two hours. Using the hair dryer and scraping out the old glue were tedious, but the plastic spudger was just the right tool for glue scraping.
Wear safety glasses while picking broken bits of glass out of the plastic frame. Do it over a piece of paper or a towel.
iPhone 3G and 3GS Front Panel Adhesive Strips
iPhone 3GS Front Panel